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1

Synthesis and characterization of dextran-capped silver nanoparticles with enhanced antibacterial activity.  

PubMed

Dextran-capped silver nanoparticles were synthesized by reducing silver nitrate with NaBH4 in the presence of dextran as capping agent. The characters of silver nanoparticles were investigated using UV-Vis spectrophotometer, nano-grainsize analyzer, X-ray diffraction, and transmission electron microscopy. Results showed that the silver nanoparticles capped with dextran were in uniform shape and narrow size distribution. Moreover, compared with polyvinylpyrrolidone (PVP)-capped silver nanoparticles, the dextran-capped ones possessed better stability. Antibacterial tests of these silver nanoparticles were carried out for Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Results suggested that the dextran-capped silver nanoparticles had high antibacterial activity against both Gram-positive and Gram-negative bacteria. In addition, the cytotoxicity in vitro of the dextran-capped silver nanoparticles was investigated using mouse fibrosarcoma cells (L929). The toxicity was evaluated by the changes of cell morphology and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. Results indicated that these silver nanoparticles had slight effect on the survival and proliferation of L-929 cells at their minimal inhibitory concentration (MIC). After modified by dextran, the physiochemical properties of the silver nanoparticles had been improved. We anticipated that these dextran-capped silver nanoparticles could be integrated into systems for biological and pharmaceutical applications. PMID:22852305

Yang, Guili; Lin, Qiuxia; Wang, Chunren; Li, Junjie; Wang, Jian; Zhou, Jin; Wang, Yan; Wang, Changyong

2012-05-01

2

Mobility of capped silver nanoparticles under environmentally relevant conditions.  

PubMed

The mobility and deposition of capped silver (Ag) nanoparticles (NPs) on silica surfaces were characterized over a wide range of pH and ionic strength (IS) conditions, including seawater and freshwater. Two common organic capping agents (citrate and PVP) were evaluated. Both the capped Ag NPs and the silica surfaces were negatively charged under these environmentally relevant conditions, resulting in net repulsive electrostatics under most conditions. The steric repulsion introduced by the capping agents significantly reduced aggregation and deposition. In addition, the presence of natural organic matter in solution further decreased the deposition of either Ag NP on silica. Ag NPs were found to be highly mobile under these environmentally relevant conditions, with little or no deposition. PMID:22133047

Thio, Beng Joo Reginald; Montes, Milka O; Mahmoud, Mahmoud A; Lee, Dong-Woog; Zhou, Dongxu; Keller, Arturo A

2012-07-01

3

Synthesis and In-Vitro Antimycobacterial Studies of Cysteine Capped silver NanoParticles  

Microsoft Academic Search

Nanoparticles are widely used for targeted drug delivery and for other biomedical applications. Particularly silver nanoparticles have gained much importance in nanobiotechnology due to their antimicrobial activity. In the present study, a novel nanobioconjugate of silver and cysteine has been prepared to study the antimycobacterial activity. This is the first ever study wherein Ag nano-particles have been capped by cysteine,

Mithun V. Varghese; Ravindra S. Dhumal; Sharvil S. Patil; Anant R. Paradkar; Pawan K. Khanna

2009-01-01

4

Activity of catalytic silver nanoparticles modulated by capping agent hydrophobicity.  

PubMed

In this paper, a facile in situ method is reported for the preparation of catalytic silver nanoparticles (AgNPs) using N-acyl tyramine (NATA) with variable hydrophobic acyl length. Scanning electron microscopic analysis shows that NATA exists initially as larger aggregates in alkaline aqueous solution. The addition of AgNO3 dissociates these larger aggregate and subsequently promotes the formation of self-assembled NATA and AgNPs. Characterization of AgNPs using UV-vis spectroscopy, scanning electron microscope and transmission electron microscope revealed that the hydrophobic acyl chain length of NATA does not influence the particle size, shape and morphology. All NATA-AgNPs yielded relatively identical values in full width at half-maximum (FWHM) analysis, indicating that the AgNPs prepared with NATA are relatively polydispersed at all tested acyl chain lengths. These nanoparticles are able to efficiently catalyze the reduction of 4-nitro phenol to 4-amino phenol, 2-nitro aniline to 1,2-diamino benzene, 2,4,6-trinitro phenol to 2,4,6-triamino phenol by NaBH4 in an aqueous environment. The reduction reaction rate is determined to be pseudo-first order and the apparent rate constant is linearly dependent on the hydrophobic acyl chain length of the NATA. All reaction kinetics presented an induction period, which is dependent on the N-acyl chain length, indicating that the hydrophobic effects play a critical role in bringing the substrate to the metal nanoparticle surface to induce the catalytic reaction. In this study, however, the five catalytic systems have similar size and polydispersity, differing only in terms of capping agent hydrophobicity, and shows different catalytic activity with respect to the alkyl chain length of the capping agent. As discussed, the ability to modulate the metal nanoparticles catalytic property, by modifying the capping agent hydrophobicity represents a promising future for developing an efficient nanocatalyst without altering the size, shape and morphology of the nanoparticles. PMID:24698147

Janani, Seralathan; Stevenson, Priscilla; Veerappan, Anbazhagan

2014-05-01

5

High yield synthesis of pure alkanethiolate-capped silver nanoparticles.  

PubMed

One-phase, one-pot synthesis of Ag(0) nanoparticles capped with alkanethiolate molecules has been optimized to easily achieve a pure product in quantitative yield. We report the synthesis of dodecanethiolate-capped silver particles and the chemophysical, structural, and morphologic characterization performed by way of UV-vis, (1)H NMR, and X-ray photoelectron (XPS) spectroscopies, X-ray powder diffraction (XRD) and X-ray absorption fine structure analysis (XFAS), electron diffraction and high-resolution transmission electron microscopy (HR-TEM), and scanning and transmission electron microscopy (SEM and TEM). Depending on the molar ratio of the reagents (dodecylthiosulphate/Ag(+)), the mean Ag(0) particle size D(XRD) is tuned from 4 to 3 nm with a narrow size distribution. The particles are highly soluble, very stable in organic solvents (hexane, toluene, dichloromethane, etc.), and resistant to oxidation; the hexane solution after one year at room temperature does not show any precipitation or formation of oxidation byproducts. PMID:20822171

Mari, Alessandra; Imperatori, Patrizia; Marchegiani, Giada; Pilloni, Luciano; Mezzi, Alessio; Kaciulis, Saulius; Cannas, Carla; Meneghini, Carlo; Mobilio, Settimio; Suber, Lorenza

2010-10-01

6

CTAB capped silver nanoparticles for plasmonic dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

To improve the light harvesting efficiency of Dye-sensitized solar cell (DSSC), we have explored the surface plasmon property of metal nanoparticles in this paper. Cetyl trimethylammonium bromide (CTAB) capped silver nanoparticles have been synthesized by wet chemical method and studied for spectroscopic and structural investigations. FTIR confirms the capping of CTAB on silver nanoparticles occurs via their head group. Williamson Hall plot revealed the presence of tensile strain. Finally, these particles have been incorporated in DSSC to study the plasmonic effect of nanoparticles on performance of DSSC.

Tanvi, Mahajan, Aman; Bedi, R. K.; Kumar, Subodh

2014-04-01

7

Laser-fabricated castor oil-capped silver nanoparticles  

PubMed Central

Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time.

Zamiri, Reza; Zakaria, Azmi; Abbastabar, Hossein; Darroudi, Majid; Husin, Mohd Shahril; Mahdi, Mohd Adzir

2011-01-01

8

Laser-fabricated castor oil-capped silver nanoparticles.  

PubMed

Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time. PMID:21698083

Zamiri, Reza; Zakaria, Azmi; Abbastabar, Hossein; Darroudi, Majid; Husin, Mohd Shahril; Mahdi, Mohd Adzir

2011-01-01

9

Spectroscopic investigation of S-Ag interaction in ?-mercaptoundecanoic acid capped silver nanoparticles  

NASA Astrophysics Data System (ADS)

This paper deals with the synthesis of ?-mercaptoundecanoic acid (MUA) capped silver nanoparticles (NPs) with an average size of 15 nm by citrate reduction technique and spectroscopic investigation of S-Ag interaction. We have studied the interaction of thiol with silver NPs in aqueous medium by employing UV-vis, Raman, FT-IR, and photoluminescence spectroscopy. The shifting of silver surface plasmon band in the UV-vis spectra shows the stabilization of the silver nanoparticles by MUA. The disappearance of S-H stretching in both the FT-IR and Raman spectra and the shifting of the NMR signals of the protons in close proximity to the metal center supported the existence of the S-Ag interaction in MUA capped silver NPs. The morphology of the thiol protected silver NPs was investigated by transmission electron microscopy (TEM) and was found to be distinct and spherical entities.

Tripathy, Suraj Kumar; Yu, Yeon-Tae

2009-05-01

10

Preparation of linoleic acid-capped silver nanoparticles and their antimicrobial effect.  

PubMed

Silver nanoparticles have been prepared through the chemical reduction of silver ions by ethanol using linoleic acid as a stabilising agent. This colloidal solution shows an absorption band in the visible range with an absorption peak at 421 nm. The peaks in the X-ray diffraction (XRD) pattern matches well with the standard values of the face-centred-cubic form of metallic silver. Transmission Electron Microscope (TEM) micrograph shows a nearly uniform distribution of the particles with an average size of 8 nm. This linoleic acid-capped silver nanoparticles show antimicrobial activity against Escherichia coli and Staphylococcus aureus. PMID:22559712

Das, R; Gang, S; Nath, S S; Bhattacharjee, R

2012-06-01

11

Biomimetic synthesis and characterisation of protein capped silver nanoparticles.  

PubMed

A controlled and up-scalable route for the biosynthesis of silver nanopartilces (NPs) mediated by fungal proteins of Coriolus versicolor has been undertaken for the first time. The fungus when challenged with silver nitrate solution accumulated silver NPs on its surface in 72h which could be reduced to 1h by tailoring the reaction conditions. Under alkaline conditions, the reaction was much faster and could easily proceed at room temperature even without stirring. The resulting Ag NPs displayed controllable structural and optical properties depending on the experimental parameters such as pH and reaction temperatures. The average size, morphology, and structure of particles were determined by AFM, TEM, XRD and UV/Visible absorption spectrophotometry. Fourier transform infrared study disclosed that the amino groups were bound to the particles, which was accountable for the stability of NPs. It further confirmed the presence of protein as the stabilizing and capping agent surrounding the silver NPs. Experiments were conducted both with, media in which fungus was initially harvested and that of pristine fungal mycelium alone. Under normal conditions, in the case of media extracellular synthesis took place whereby other than the fungal proteins, glucose was also responsible for the reduction. In the case of fungal mycelium, the intracellular formation of Ag NPs, could be tailored to give both intracellular and extracellular Ag NPs under alkaline conditions whereby the surface S-H groups of the fungus played a major role. PMID:18625550

Sanghi, Rashmi; Verma, Preeti

2009-01-01

12

Gellan gum capped silver nanoparticle dispersions and hydrogels: cytotoxicity and in vitro diffusion studies.  

PubMed

The preparation of highly stable water dispersions of silver nanoparticles using the naturally available gellan gum as a reducing and capping agent is reported. Further, exploiting the gel formation characteristic of gellan gum silver nanoparticle incorporated gels have also been prepared. The optical properties, morphology, zeta potential and long-term stability of the synthesized silver nanoparticles were investigated. The superior stability of the gellan gum-silver nanoparticle dispersions against pH variation and electrolyte addition is revealed. Finally, we studied the cytotoxicity of AgNP dispersions in mouse embryonic fibroblast cells (NIH3T3) and also evaluated the in vitro diffusion of AgNP dispersions/gels across rat skin. PMID:22134682

Dhar, S; Murawala, P; Shiras, A; Pokharkar, V; Prasad, B L V

2012-01-21

13

Control of biofilm formation in water using molecularly capped silver nanoparticles  

Microsoft Academic Search

Control of biofouling and its negative effects on process performance of water systems is a serious operational challenge in all of the water sectors. Molecularly capped silver nanoparticles (Ag-MCNPs) were used as a pretreatment strategy for controlling biofilm development in aqueous suspensions using the model organism Pseudomonas aeruginosa. Biofilm control was tested in a two-step procedure: planktonic P. aeruginosa was

A. Dror-Ehre; A. Adin; G. Markovich; H. Mamane

2010-01-01

14

Sweeter but deadlier: decoupling size, charge and capping effects in carbohydrate coated bactericidal silver nanoparticles.  

PubMed

Silver nanoparticles are widely used due to their biomedical-antibacterial applications. At the same time, the stabilization of these nanoparticles is challenging and may be made using polymeric carbohydrates, based on the practice of avoiding toxic chemicals and undesirable residues. In this study, we synthesized silver nanoparticles (AgNPs) which were stabilized by carbohydrates (potato starch and chitosan) and characterized by UV-Vis spectroscopy, zeta potential and transmission electron microscopy techniques. Bactericidal efficiency of AgNPs capped with different carbohydrates was tested demonstrating that the synthesized materials were able to inhibit the growth of two clinical/medical relevant bacteria strains (Escherichia coil and Staphylococcus aureus). AgNPs stabilized by chitosan presented enhanced bactericidal activity if compared to the ones synthesized in presence of potato starch. This difference is mainly attributed to the known antibacterial properties of chitosan associated to overall positive charge of the nanoparticles capped by this polymer. Those nanoparticles obtained in presence of starch presented minor bactericidal effects since the starch-capping agent is not able to contribute to the avoidance of bacteria growth and confers a quasi-neutral charge to the nanoparticle. PMID:24059081

de Oliveira, Luciane França; Gonçalves, Julianna de Oliveira; Gonçalves, Kaliandra de Almeida; Kobarg, Jörg; Cardoso, Mateus Borba

2013-11-01

15

Hydroxy propyl cellulose capped silver nanoparticles produced by simple dialysis process  

SciTech Connect

Silver (Ag) nanoparticles ({approx}6 nm) were synthesized using a novel dialysis process. Silver nitrate was used as a starting precursor, ethylene glycol as solvent and hydroxy propyl cellulose (HPC) introduced as a capping agent. Different batches of reaction mixtures were prepared with different concentrations of silver nitrate (AgNO{sub 3}). After the reduction and aging, these solutions were subjected to ultra-violet visible spectroscopy (UVS). Optimized solution, containing 250 mg AgNO{sub 3} revealed strong plasmon resonance peak at {approx}410 nm in the spectrum indicating good colloidal state of Ag nanoparticles in the diluted solution. The optimized solution was subjected to dialysis process to remove any unreacted solvent. UVS of the optimized solution after dialysis showed the plasmon resonance peak shifting to {approx}440 nm indicating the reduction of Ag ions into zero-valent Ag. This solution was dried at 80 {sup o}C and the resultant HPC capped Ag (HPC/Ag) nanoparticles were studied using transmission electron microscopy (TEM) for their particle size and morphology. The particle size distribution (PSD) analysis of these nanoparticles showed skewed distribution plot with particle size ranging from 3 to 18 nm. The nanoparticles were characterized for phase composition using X-ray diffractrometry (XRD) and Fourier transform infrared spectroscopy (FT-IR).

Francis, L. [University of Genova, Department of Chemistry and Industrial Chemistry, via Dodecaneso 31, 16146 Genova (Italy)] [University of Genova, Department of Chemistry and Industrial Chemistry, via Dodecaneso 31, 16146 Genova (Italy); Balakrishnan, A. [Laboratoire SIMaP - GPM2, Grenoble-INP/UJF/CNRS BP46, 38042 Saint Martin d'Heres cedex (France)] [Laboratoire SIMaP - GPM2, Grenoble-INP/UJF/CNRS BP46, 38042 Saint Martin d'Heres cedex (France); Sanosh, K.P. [Department of Innovation Engineering, University of Lecce, via per Monteroni, 73100 Lecce (Italy)] [Department of Innovation Engineering, University of Lecce, via per Monteroni, 73100 Lecce (Italy); Marsano, E., E-mail: marsano@chimica.unige.it [University of Genova, Department of Chemistry and Industrial Chemistry, via Dodecaneso 31, 16146 Genova (Italy)

2010-08-15

16

Formation of colloidal silver nanoparticles: Capping action of citrate  

SciTech Connect

Colloidal silver sols of long-time stability are formed in the {gamma}-irradiation of 1.0 x 10{sup {minus}4} M AgClO{sub 4} solutions, which also contain 0.3 M 2-propanol, 2.5 x 10{sup {minus}2} M N{sub 2}O, and sodium citrate in various concentrations. The reduction of Ag{sup +} in these solutions is brought about by the 1-hydroxyalkyl radical generated in the radiolysis of 2-propanol; citrate does not act as a reductant but solely as a stabilizer of the colloidal particles formed. Its concentration is varied in the range from 5.0 x 10{sup {minus}5} to 1.5 x 10{sup {minus}3} M, and the size and size distribution of the silver particles are studied by electron microscopy. At low citrate concentration, partly agglomerated large particles are formed that have many imperfections. In an intermediate range (a few 10{sup {minus}4} M), well-separated particles with a rather narrow size distribution and little imperfections are formed, the size slightly decreasing with increasing citrate concentration. At high citrate concentrations, large lumps of coalesced silver particles are present, due to destabilization by the high ionic strength of the solution. These findings are explained by two growth mechanisms: condensation of small silver clusters (type-1 growth), and reduction of Ag{sup +} on silver particles via radical-to-particle electron transfer (type-2 growth). The particles formed in the intermediate range of citrate concentration were studied by high-resolution electron microscopy and computer simulations. They constitute icosahedra and cuboctahedra.

Henglein, A.; Giersig, M.

1999-11-04

17

Formation of colloidal silver nanoparticles: Capping action of citrate  

Microsoft Academic Search

Colloidal silver sols of long-time stability are formed in the γ-irradiation of 1.0 x 10⁻⁴ M AgClOâ solutions, which also contain 0.3 M 2-propanol, 2.5 x 10⁻² M NâO, and sodium citrate in various concentrations. The reduction of Ag{sup +} in these solutions is brought about by the 1-hydroxyalkyl radical generated in the radiolysis of 2-propanol; citrate does not act

Arnim Henglein; Michael Giersig

1999-01-01

18

Green synthesis of chondroitin sulfate-capped silver nanoparticles: Characterization and surface modification.  

PubMed

A one-step route for the green synthesis of highly stable and nanosized silver metal particles with narrow distribution is reported. In this environmentally friendly synthetic method, silver nitrate was used as silver precursor and biocompatible chondroitin sulfate (ChS) was used as both reducing agent and stabilizing agent. The reaction was carried out in a stirring aqueous medium at the room temperature without any assisted by microwave, autoclave, laser irradiation, ?-ray irradiation or UV irradiation. The transparent colorless solution was converted to the characteristics light red then deep red-brown color as the reaction proceeds, indicating the formation of silver nanoparticles (Ag NPs). The Ag NPs were characterized by UV-visible spectroscopy (UV-vis), photon correlation spectroscopy, laser Doppler anemometry, transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The results demonstrated that the obtained metallic nanoparticles were Ag NPs capped with ChS. In this report, dynamic light scattering (DLS) was used as a routinely analytical tool for measuring size and distribution in a liquid environment. The effects of the reaction time, reaction temperature, concentration and the weight ratio of ChS/Ag(+) on the particle size and zeta potential were investigated. The TEM image clearly shows the morphology of the well-dispersed ChS-capped Ag NPs are spherical in shape, and the average size (<20nm) is much smaller than the Z-average value (76.7nm) measured by DLS. Meanwhile, the ChS-capped Ag NPs coated with N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) were prepared by an ionic gelation method and the surface charge of Ag NPs was switched from negative to positive. PMID:24906746

Cheng, Kuang-Ming; Hung, Yao-Wen; Chen, Cheng-Cheung; Liu, Cheng-Che; Young, Jenn-Jong

2014-09-22

19

Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity  

PubMed Central

In this study, a ‘green chemistry’ approach was introduced to synthesize silk sericin (SS)-capped silver nanoparticles (AgNPs) under an alkaline condition (pH 11) using SS as a reducing and stabilizing agent instead of toxic chemicals. The SS-capped AgNPs were successfully synthesized at various concentrations of SS and AgNO3, but the yields were different. A higher yield of SS-capped AgNPs was obtained when the concentrations of SS and AgNO3 were increased. The SS-capped AgNPs showed a round shape and uniform size with diameter at around 48 to 117 nm. The Fourier transform infrared (FT-IR) spectroscopy result proved that the carboxylate groups obtained from alkaline degradation of SS would be a reducing agent for the generation of AgNPs while COO? and NH2?+ groups stabilized the AgNPs and prevented their precipitation or aggregation. Furthermore, the SS-capped AgNPs showed potent anti-bacterial activity against various gram-positive bacteria (minimal inhibitory concentration (MIC) 0.008 mM) and gram-negative bacteria (MIC ranging from 0.001 to 0.004 mM). Therefore, the SS-capped AgNPs would be a safe candidate for anti-bacterial applications.

2014-01-01

20

Partial aggregation of silver nanoparticles induced by capping and reducing agents competition.  

PubMed

It is well known that nanomaterials properties and applications are dependent on the size, shape, and morphology of these structures. Among nanomaterials, silver nanoparticles (AgNPs) have attracted attention since they have considerably versatile properties, such as a variable surface area to volume ratio, which is very useful for many biomedical and technological applications. Within this scenario, small nanoparticle aggregates can have their properties reduced due to the increased size and alterations in their shape/morphology. In this work, silver nanoparticles aggregation was studied through chemical reduction of silver nitrate in the presence of sodium borohydride (reducing agent) and sodium citrate (capping agent). By changing the amount of reducing agent along the reaction, unaggregated and partially aggregated samples were obtained and characterized by UV-vis, zeta potential, and SAXS techniques. pH was measured in every step of the reaction in order to correlate these results with those obtained from structural techniques. Addition of the reducing agent first causes the reduction of Ag(+) to silver nanoparticles. For higher concentrations of sodium borohydrate, the average AgNPs size is increased and NPs aggregation is observed. It was found that zeta potential and pH values have a strong influence on AgNPs formation, since reducing agent addition can induce partial removal of citrate weakly associated on the AgNPs surface and increase the ionic strength of the solution, promoting partial aggregation of the particles. This aggregation state was duly identified by coupling SAXS, zeta potential and pH measurements. In addition, the SAXS technique showed that aggregates formed along the process are elongated-like particles due to the exponential decay evidenced through SAXS curves. PMID:24328925

de Oliveira, Jessica Fernanda Affonso; Cardoso, Mateus Borba

2014-05-01

21

Influence of pH on the properties of PVA capped silver nanoparticles  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were synthesized by chemical reduction method using ascorbic acid as reductant and PVA as surfactant and studied the pH influence on the structural, compositional and optical properties of silver nanoparticles. Broadened XRD peaks confirmed the formation of small nanosized silver nanoparticles with face centered cubic (FCC) structure. The particle size decreased with increasing pH value. We have observed blue shift of Surface Plasmon Resonance (SPR) band from optical absorption spectra. The obtained nanoparticles were well dispersed in water, ethanol and polar solvents and thus more suitable for biocompatible.

Ajitha, B.; Reddy, P. Sreedhara

2013-06-01

22

Improving SERS Activity of Inositol Hexaphosphate Capped Silver Nanoparticles: Fe(3+) as a Switcher.  

PubMed

Inositol hexaphosphate (IP6) capped silver nanoparticles (IP6@AgNPs) were fabricated as surface-enhanced Raman scattering (SERS) active substrates. SERS activity of IP6@AgNPs could be further improved via adding due amounts of Fe(3+) to form Fe(3+)-IP6@AgNPs. The mechanism of Fe(3+)-induced SERS improvement of IP6@AgNPs can be attributed to the strong interaction of IP6 and Fe(3+), which leads to controllable adjustment of the gap among neighboring nanoparticles to produce "hot spots". The above mechanism was confirmed with ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscope (TEM), dynamic light scattering (DLS), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Such Fe(3+)-IP6@AgNPs-based SERS system was used to detect Rhodamine 6G (R6G) down to the trace level of 10(-10) mol L(-1). Besides, New Fuchsin (NF) was also used as a Raman probe to calculate the enhancement factor (EF) of IP6@AgNPs without and with Fe(3+). The SERS activity of IP6@AgNPs happened extreme decrease after one-year storage and could be recovered to great extent aided by the addition of Fe(3+). The Fe(3+) optimized IP6@AgNPs system could be applied to detect thymine at trace level by SERS. PMID:25010733

Guo, Xiaoyu; Fu, Yichen; Fu, Shuyue; Wang, Hui; Yang, Tianxi; Wen, Ying; Yang, Haifeng

2014-07-21

23

A new, simple, green, and one-pot four-component synthesis of bare and poly(?,?, L-glutamic acid)-capped silver nanoparticles  

PubMed Central

A simple and green chemical method has been developed to synthesize stable bare and capped silver nanoparticles based on the reduction of silver ions by glucose and capping by poly(?,?,L-glutamic acid) (PGA). The use of ammonia during synthesis was avoided. PGA has had a dual role in the synthesis and was used as a capping agent to make the silver nanoparticle more biocompatible and to protect the nanoparticles from agglomerating in the liquid medium. The synthesized PGA-capped silver nanoparticles in the size range 5–45 nm were stable over long periods of time, without signs of precipitation. Morphological examination has shown that the silver nanoparticles had a nearly spherical, multiply twinned structure. The effects of the reaction temperature and the reaction time during the synthesis were investigated too. The biocompatibility of the PGA-capped silver nano-particles is discussed in terms of in vitro toxicity with human intestinal Caco-2 cells. The samples were characterized by UV–Visible spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurements.

Savanovic, Igor; Uskokovic, Vuk; Skapin, Sreco D.; Bracko, Ines; Jovanovic, Uros; Uskokovic, Dragan

2013-01-01

24

Enhancement of Antibacterial Activity of Capped Silver Nanoparticles in Combination with Antibiotics, on Model Gram-Negative and Gram-Positive Bacteria  

PubMed Central

The nanoparticles used in this study were prepared from AgNO3 using NaBH4 in the presence of capping agents such as citrate, sodium dodecyl sulfate, and polyvinylpyrrolidone. The formed nanoparticles were characterized with UV-Vis, TEM, and XRD. The generation of silver nanoparticles was confirmed from the appearance of yellow colour and an absorption maximum between 399 and 404?nm. The produced nanoparticles were found to be spherical in shape and polydisperse. For citrate, SDS, and PVP capped nanoparticles, the average particle sizes were 38.3 ± 13.5, 19.3 ± 6.0, and 16.0 ± 4.8?nm, respectively. The crystallinity of the nanoparticles in FCC structure is confirmed from the SAED and XRD patterns. Also, the combined antibacterial activity of these differently capped nanoparticles with selected antibiotics (streptomycin, ampicillin, and tetracycline) was evaluated on model Gram-negative and Gram-positive bacteria, employing disc diffusion assay. The activity of the tested antibiotics was enhanced in combination with all the stabilized nanoparticles, against both the Gram classes of bacteria. The combined effects of silver nanoparticles and antibiotics were more prominent with PVP capped nanoparticles as compared to citrate and SDS capped ones. The results of this study demonstrate potential therapeutic applications of silver nanoparticles in combination with antibiotics.

Kora, Aruna Jyothi; Rastogi, Lori

2013-01-01

25

Biopolymer capped silver nanoparticles as fluorophore for ultrasensitive and selective determination of malathion.  

PubMed

This paper describes a novel luminescent sensor for malathion using chitosan capped silver nanoparticles (Chi-AgNPs) as fluorophore. The Chi-AgNPs were synthesized by the wet-chemical method and were characterized by absorption, fluorescence, HR-TEM, XRD and DLS techniques. The Chi-AgNPs show the absorption maximum at 394 nm and emission maximum at 536 nm. While adding 10 µM malathion, yellow color Chi-AgNPs was changed to brown and the absorbance was decreased along with a redshift. The observed spectral and color changes were mainly due to the aggregation of Chi-AgNPs. This was confirmed by zeta potential, DLS and HR-TEM studies. No significant absorption spectral change was observed for Chi-AgNPs in the presence of less than micromolar concentrations of malathion. However, the emission intensity of Chi-AgNPs was decreased and the emission maximum was shifted toward higher wavelength in the presence of picomolar concentration of malathion. Based on the decrease in emission intensity, the concentration of malathion was determined. The Stern-Volmer constant, Gibbs free energy change, association constant, quantum yield and binding constant were calculated and the quenching mechanism was proposed. The Chi-AgNPs show good selectivity toward the determination of 10nM malathion in the presence of 1000-fold higher concentrations of common interferents. A good linearity was observed for the emission intensity against 1 × 10(-9)-10 × 10(-12)M malathion and the detection limit was found to be 94 fM L(-1) (S/N=3). The proposed method was successfully applied to determine malathion in fruits and water samples and the obtained results were validated with HPLC. PMID:24054557

Vasimalai, N; Abraham John, S

2013-10-15

26

Discriminatory antibacterial effects of calix[n]arene capped silver nanoparticles with regard to gram positive and gram negative bacteria.  

PubMed

Silver nanoparticles capped with nine different sulphonated calix[n]arenes were tested for their anti-bacterial effects against B. subtilis and E. coli at an apparent concentration of 100 nM in calix[n]arene. The results show the para-sulphonato-calix[n]arenes are active against Gram positive bacteria and the derivatives having sulphonate groups at both para and alkyl terminal positions are active against Gram negative bacteria. The calix[6]arene derivative with only O-alkyl sulphonate groups shows bactericidal activity. PMID:23831853

Boudebbouze, Samira; Coleman, Anthony W; Tauran, Yannick; Mkaouar, Hela; Perret, Florent; Garnier, Alexandrine; Brioude, Arnaud; Kim, Beomjoon; Maguin, Emmanuelle; Rhimi, Moez

2013-08-18

27

Ultrasound assisted green synthesis of poly(vinyl alcohol) capped silver nanoparticles for the study of its antifilarial efficacy  

NASA Astrophysics Data System (ADS)

Poly(vinyl alcohol) (PVA) capped stable silver nanoparticles (AgNP) have been synthesized sonochemically with the help of catalytic amount of a biomolecule (tyrosine). An attempt has been made to reduce the harmfull chemical additives (like sodium borohydride, hydrazine, dimethyl formamide, etc.) used in conventional methods. Tyrosine shows excellent reducing activity in presence of PVA stabilizer. Ultra-sound increased the reaction rate and yield, and improved the quality of the AgNP in terms of regular size distribution. The synthetic route follows the principles of green chemistry. Bioactivity has been tested in the light of antifilarial efficacy through induction of apoptosis. The biocompatible polymer (PVA) capped AgNPs are suitable for the treatment of filarial nematode.

Saha, Swadhin Kr.; Chowdhury, Pranesh; Saini, Prasanta; Babu, Santi P. Sinha

2014-01-01

28

Effect of poly-?, ?, L-glutamic acid as a capping agent on morphology and oxidative stress-dependent toxicity of silver nanoparticles  

PubMed Central

Highly stable dispersions of nanosized silver particles were synthesized using a straightforward, cost-effective, and ecofriendly method. Nontoxic glucose was utilized as a reducing agent and poly-?, ?, L-glutamic acid (PGA), a naturally occurring anionic polymer, was used as a capping agent to protect the silver nanoparticles from agglomeration and render them biocompatible. Use of ammonia during synthesis was avoided. Our study clearly demonstrates how the concentration of the capping agent plays a major role in determining the dimensions, morphology, and stability, as well as toxicity of a silver colloidal solution. Hence, proper optimization is necessary to develop silver colloids of narrow size distribution. The samples were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurement. MTT assay results indicated good biocompatibility of the PGA-capped silver nanoparticles. Formation of intracellular reactive oxygen species was measured spectrophotometrically using 2,7-dichlorofluorescein diacetate as a fluorescent probe, and it was shown that the PGA-capped silver nanoparticles did not induce intracellular formation of reactive oxygen species.

Stevanovic, Magdalena; Kovacevic, Branimir; Petkovic, Jana; Filipic, Metka; Uskokovic, Dragan

2011-01-01

29

Biocidal activity of plasma modified electrospun polysulfone mats functionalized with polyethyleneimine-capped silver nanoparticles.  

PubMed

The incorporation of silver nanoparticles (AgNPs) into polymeric nanofibers has attracted a great deal of attention due to the strong antimicrobial activity that the resulting fibers exhibit. However, bactericidal efficacy of AgNP-coated electrospun fibrous mats has not yet been demonstrated. In this study, polysulfone (PSf) fibers were electrospun and surface-modified using an oxygen plasma treatment, which allowed for facile irreversible deposition of cationically charged polyethyleneimine (PEI)-AgNPs via electrostatic interactions. The PSf-AgNP mats were characterized for relative silver concentration as a function of plasma treatment time using ICP-MS and changes in contact angle. Plasma treatment of 60 s was the shortest time required for maximum loss of bacteria (Escherichia coli) viability. Time-dependent bacterial cytotoxicity studies indicate that the optimized PSf-AgNP mats exhibit a high level of inactivation against both gram negative bacteria, Escherichia coli, and gram positive bacteria, Bacillus anthracis and Staphylococcus aureus. PMID:21928790

Schiffman, Jessica D; Wang, Yue; Giannelis, Emmanuel P; Elimelech, Menachem

2011-11-01

30

Toxicity of Citrate-Capped Silver Nanoparticles in Common Carp (Cyprinus carpio)  

PubMed Central

Juvenile common carp (Cyprinus carpio) were used as a model to investigate acute toxicity and oxidative stress caused by silver nanoparticles (Ag-NPs). The fish were exposed to different concentrations of Ag-NPs for 48 h and 96 h. After exposure, antioxidant enzyme levels were measured, including glutathione-S-transferase (GST), superoxidase dismutase, and catalase (CAT). Other biochemical parameters and histological abnormalities in different tissues (i.e., the liver, gills, and brain) were also examined. The results showed that Ag-NPs agglomerated in freshwater used during the exposure experiments, with particle size remaining <100?nm. Ag-NPs had no lethal effect on fish after 4 days of exposure. Biochemical analysis showed that enzymatic activities in the brain of the fish exposed to 200??g/L of Ag-NPs were significantly reduced. Varied antioxidant enzyme activity was recorded in the liver and gills. Varied antioxidant enzyme activity was recorded for CAT in the liver and GST in the gills of the fish. However, the recovery rate of fish exposed to 200??g/L of Ag-NPs was slower than when lower particle concentrations were used. Other biochemical indices showed no significant difference, except for NH3 and blood urea nitrogen concentrations in fish exposed to 50??g/L of Ag-NPs. This study provides new evidence about the effects of nanoparticles on aquatic organisms.

Lee, Byoungcheun; Duong, Cuong Ngoc; Cho, Jaegu; Lee, Jaewoo; Kim, Kyungtae; Seo, Youngrok; Kim, Pilje; Choi, Kyunghee; Yoon, Junheon

2012-01-01

31

Poly(ethylene) glycol-capped silver and magnetic nanoparticles: synthesis, characterization, and comparison of bactericidal and cytotoxic effects.  

PubMed

Silver and magnetic (Fe3O4) nanoparticles have attracted wide attention as novel antimicrobial agents due to their unique chemical and physical properties. In order to study the comparative effects on antibacterial and animal cytotoxicity, Staphylococcus aureus and NIH 3T3 fibroblasts were used, respectively. Both nanoparticles were synthesized via a novel matrix-mediated method using poly(ethylene) glycol. Formation of silver nanoparticles was confirmed by fluorescence and ultraviolet-visible spectroscopic techniques. The poly(ethylene) glycol-coated silver and Fe3O4 nanoparticles were characterized by scanning electron microscope, transmission electron microscope, zeta potential, particle size analysis, Fourier-transform infrared, X-ray diffraction, and X-ray photoelectron spectroscopy. The antimicrobial results indicate that both poly(ethylene) glycol-coated silver and Fe3O4 nanoparticles inhibited S. aureus growth at the concentrations of 5 and 10?µg/mL at all time points without showing any significant cytotoxicity on NIH 3T3 fibroblasts. The particle size of both the poly(ethylene) glycol-coated silver and Fe3O4 nanoparticles dominated in the range 10-15?nm, obtained by particle size analyzer. The poly(ethylene) glycol coating on the particles showed less aggregation of nanoparticles, as observed by scanning electron microscope and transmission electron microscope. The overall obtained results indicated that these two nanoparticles were stable and could be used to develop a magnetized antimicrobial scaffolds for biomedical applications. PMID:23959858

Mandal, A; Sekar, S; Chandrasekaran, N; Mukherjee, A; Sastry, T P

2013-11-01

32

Gum arabic capped-silver nanoparticles inhibit biofilm formation by multi-drug resistant strains of Pseudomonas aeruginosa.  

PubMed

Clinical isolates (n?=?55) of Pseudomonas aeruginosa were screened for the extended spectrum ?-lactamases and metallo-?-lactamases activities and biofilm forming capability. The aim of the study was to demonstrate the antibiofilm efficacy of gum arabic capped-silver nanoparticles (GA-AgNPs) against the multi-drug resistant (MDR) biofilm forming P. aeruginosa. The GA-AgNPs were characterized by UV-spectroscopy, X-ray diffraction, and high resolution-transmission electron microscopy analysis. The isolates were screened for their biofilm forming ability, using the Congo red agar, tube method and tissue culture plate assays. The biofilm forming ability was further validated and its inhibition by GA-AgNPs was demonstrated by performing the scanning electron microscopy (SEM) and confocal laser scanning microscopy. SEM analysis of GA-AgNPs treated bacteria revealed severely deformed and damaged cells. Double fluorescent staining with propidium iodide and concanavalin A-fluorescein isothiocyanate concurrently detected the bacterial cells and exopolysaccharides (EPS) matrix. The CLSM results exhibited the GA-AgNPs concentration dependent inhibition of bacterial growth and EPS matrix of the biofilm colonizers on the surface of plastic catheters. Treatment of catheters with GA-AgNPs at 50?µg?ml(-1) has resulted in 95% inhibition of bacterial colonization. This study elucidated the significance of GA-AgNPs, as the next generation antimicrobials, in protection against the biofilm mediated infections caused by MDR P. aeruginosa. It is suggested that application of GA-AgNPs, as a surface coating material for dispensing antibacterial attributes to surgical implants and implements, could be a viable approach for controlling MDR pathogens after adequate validations in clinical settings. PMID:24403133

Ansari, Mohammad Azam; Khan, Haris Manzoor; Khan, Aijaz Ahmed; Cameotra, Swaranjit Singh; Saquib, Quaiser; Musarrat, Javed

2014-07-01

33

LL37 peptide@silver nanoparticles: combining the best of the two worlds for skin infection control.  

PubMed

Capping silver nanoparticles with LL37 peptide eradicates the antiproliferative effect of silver on primary skin cells, but retains the bactericidal properties of silver nanoparticles with activities comparable to silver nitrate or silver sulfadiazine. In addition, LL37 capped silver nanoparticles have anti-biofilm formation activity. PMID:24789474

Vignoni, Mariana; de Alwis Weerasekera, Hasitha; Simpson, Madeline J; Phopase, Jaywant; Mah, Thien-Fah; Griffith, May; Alarcon, Emilio I; Scaiano, Juan C

2014-06-01

34

Synthesis of Silver Nanoparticles  

NSDL National Science Digital Library

This series of videos, presented by the Materials Research Science and Engineering Center at the University of Wisconsin-Madison, deals with the synthesis of silver nanoparticles. The experiment allows students to view the formation of silver nanoparticles that can be detected by the reflection of a laser beam. Silver nanoparticles are used in the creation of yellow stained glass in churches around the country, an interesting, but little known fact. This is a fairly inexpensive activity as it involves stock solutions, and equipment present in any science laboratory. Overall, students will enjoy this basic, but still challenging, experiment.

Johnson, Chris; Ng, Steve

2009-01-21

35

Straightforward, one-step synthesis of alkanethiol-capped silver nanoparticles from an aggregative model of growth.  

PubMed

Classical nucleation theory and Derjaguin, Landau, Verwey, Overbeek (DLVO) theory for colloidal stability were applied to gain insight into the synthesis of dodecanethiol (DDT) functionalized silver nanoparticles (NPs) by reduction of silver nitrate with sodium borohydride in ethanol. This analysis indicated the importance of quickly establishing a dense DDT ligand brush on inherently unstable primary particles to achieve colloidal stability. The DLVO calculations also indicated that the electrostatic potential was a minor contributor to repulsive interactions, signifying that it would be possible to control NP size and uniformity in solutions with high ionic strength, as long as sufficient DDT was available to form a densely packed ligand layer on the NPs. These insights were applied to design a new straightforward, one-step, one-phase synthesis for the production of alkanethiol-functionalized silver NPs. To test the insights from DLVO theory, 16 samples were synthesized in the parameter space R = 3-12, S = 1-12 where R = [NaBH4]/[AgNO3], S = [DDT]/[AgNO3], and [AgNO3] = 10 mM. In general, samples with R = 3 or S = 1 were polydisperse; however, samples in the R = 6-12 and S = 3-12 range had uniform particle sizes with average diameters between 3.5 and 4.7 nm. Additionally, samples with R = 72-108 and S = 12 were synthesized to test particle stability at high ionic strength; again, uniform NPs with average diameters from 3.5 to 3.8 nm were produced. Ultimately, the insights gained from DLVO theory successfully guided the development of a one-step, one-phase technique for the synthesis of uniform, spherical alkanethiol-functionalized silver NPs. PMID:23855440

Farrell, Zachary; Shelton, Cameron; Dunn, Caroline; Green, David

2013-07-30

36

Biosynthesis of silver nanoparticles.  

PubMed

Metal nanoparticles have unique optical, electronic, and catalytic properties. There exist well-defined physical and chemical processes for their preparation. Those processes often yield small quantities of nanoparticles having undesired morphology, and involve high temperatures for the reaction and the use of hazardous chemicals. Relatively, the older technique of bioremediation of metals uses either microorganisms or their components for the production of nanoparticles. The nanoparticles obtained from bacteria, fungi, algae, plants and their components, etc. appear environment-friendly, as toxic chemicals are not used in the processes. In addition to this, the formation of nanoparticles takes place at almost normal temperature and pressure. Control of the shape and size of the nanoparticles is possible by appropriate selection of the pH and temperature. Three important steps are the bioconversion of Ag+ ions, conversion of desired crystals to nanoparticles, and nanoparticle stability. Generally, nanoparticles are characterized by the UV-visible spectroscopy and use of the electron microscope. Silver nanoparticles are used as antimicrobial agents and they possess antifungal, anti-inflammatory, and anti-angiogenic properties. This review highlights the biosynthesis of silver nanoparticles by various organisms, possible mechanisms of their synthesis, their characterization, and applications of silver nanoparticles. PMID:24749472

Poulose, Subin; Panda, Tapobrata; Nair, Praseetha P; Théodore, Thomas

2014-02-01

37

Facile size-regulated synthesis of silver nanoparticles using pectin.  

PubMed

Monodispersed silver nanoparticles capped by pectin were prepared by the reaction of silver nitrate with alkali hydrolyzed pectin at 70°C for 30min. Spherical and size-regulated silver nanoparticles were prepared using alkali hydrolyzed pectin as a reducing and particle-stabilizing agent. This approach is facile, effective, rapid, and convenient for the large scale preparation of silver nanoparticles. UV-visible spectral analysis confirmed that the nanoparticles consisted of metallic silver. Transmission electron microscopy (TEM) was used to estimate particle size and size distribution of the produced silver nanoparticles. Transmission electron microscopy and size distribution analysis revealed the presence of spherical silver nanoparticles with a main diameter of 5-10nm and have a narrow size distribution. The concentration of reducing sugars was monitored by using dinitrosalicylic acid. A comprehensive schematic mechanism for the formation of silver nanoparticles using pectin is proposed. PMID:25037438

Zahran, M K; Ahmed, Hanan B; El-Rafie, M H

2014-10-13

38

Silver nanoparticles tolerant bacteria from sewage environment.  

PubMed

Silver nanoparticle (SNP) is a threat to soil, water and human health. Protection of environment from silver nanoparticles is a major concern. A sewage isolate, Bacillus pumilus treated with SNPs showed similar growth kinetics to that without nanoparticles. A reduction in the amount of exopolysaccharides was observed after SNPs--B. pumilus culture supernatant interaction. The Fourier transform infrared spectroscopy (FT-IR) peaks for the exopolysaccharides extracted from the bacterial culture supernatant and the interacted SNPs were almost similar. The exopolysaccharide capping of the SNPs was confirmed by UV-Visible, FT-IR and X-ray diffraction analysis. The study of bacterial exopolysaccharides capped SNPs with E. coli, S. aureus and M. luteus showed less toxicity compared to uncoated SNPs. Our studies suggested that the capping of nanoparticles by bacterially produced exopolysaccharides serve as the probable mechanism of tolerance. PMID:21517011

Khan, Sudheer; Mukherjee, Amitava; Chandrasekaran, Natarajan

2011-01-01

39

Thermal decomposition as route for silver nanoparticles  

PubMed Central

Single crystalline silver nanoparticles have been synthesized by thermal decomposition of silver oxalate in water and in ethylene glycol. Polyvinyl alcohol (PVA) was employed as a capping agent. The particles were spherical in shape with size below 10 nm. The chemical reduction of silver oxalate by PVA was also observed. Increase of the polymer concentration led to a decrease in the size of Ag particles. Ag nanoparticle was not formed in the absence of PVA. Antibacterial activity of the Ag colloid was studied by disc diffusion method.

Navaladian, S; Viswanath, RP; Varadarajan, TK

2007-01-01

40

Stability of citrate-capped silver nanoparticles in exposure media and their effects on the development of embryonic zebrafish (Danio rerio)  

PubMed Central

The stability of citrate-capped silver nanoparticles (AgNPs) and the embryonic developmental toxicity were evaluated in the fish test water. Serious aggregation of AgNPs was observed in undiluted fish water (DM-100) in which high concentration of ionic salts exist. However, AgNPs were found to be stable for 7 days in DM-10, prepared by diluting the original fish water (DM-100) with deionized water to 10%. The normal physiology of zebrafish embryos were evaluated in DM-10 to see if DM-10 can be used as a control vehicle for the embryonic fish toxicity test. As results, DM-10 without AgNPs did not induce any significant adverse effects on embryonic development of zebrafish determined by mortality, hatching, malformations and heart rate. When embryonic toxicity of AgNPs was tested in both DM-10 and in DM-100, AgNPs showed higher toxicity in DM-10 than in DM-100. This means that the big-sized aggregates of AgNPs were low toxic compared to the nano-sized AgNPs. AgNPs induced delayed hatching, decreased heart rate, pericardial edema, and embryo death. Accumulation of AgNPs in the embryo bodies was also observed. Based on this study, citrate-capped AgNPs are not aggregated in DM-10 and it can be used as a control vehicle in the toxicity test of fish embryonic development.

Park, Kwangsik; Tuttle, George; Sinche, Federico; Harper, Stace L.

2014-01-01

41

Bioconjugation of colloidal silver nanoparticles  

NASA Astrophysics Data System (ADS)

We have studied bioconjugation of Bovine Serum Albumin (BSA) and DNA with colloidal silver nanoparticles. BSA and DNA modified silver nanoparticles were characterized using UV-Vis spectroscopy and FTIR studies. The emergence of new peaks in UV-Vis spectra corresponding to these biomolecules without shift in surface plasmon peak of silver nanoparticles showed successful modification of metal nanoparticles with BSA and DNA. FTIR spectra also supported these results.

Kaur, Harmandeep; Bhatnagar, Archana; Tripathi, S. K.

2013-06-01

42

Synthesis of Stable, Polyshaped Silver, and Gold Nanoparticles Using Leaf Extract of Lonicera japonica L  

Microsoft Academic Search

Silver nanoparticles and gold nanoparticles of various shapes and sizes have applications in medicine, biosensing, and catalysis. Plant-mediated synthesis is preferred due to ecofriendly nature and enhanced quality of the synthesized nanoparticles. As Lonicera japonica plant has several medicinal properties, we explored it here for the first time in the synthesis of silver nanoparticles and gold nanoparticles. Capping of synthesized

Vineet Kumar; Sudesh Kumar Yadav

2011-01-01

43

Citrate-capped silver nanoparticles showing good bactericidal effect against both planktonic and sessile bacteria and a low cytotoxicity to osteoblastic cells.  

PubMed

A common problem with implants is that bacteria can form biofilms on their surfaces, which can lead to infection and, eventually, to implant rejection. An interesting strategy to inhibit bacterial colonization is the immobilization of silver (Ag) species on the surface of the devices. The aim of this paper is to investigate the action of citrate-capped silver nanoparticles (AgNPs) on clinically relevant Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria in two different situations: (i) dispersed AgNPs (to assess the effect of AgNPs against planktonic bacteria) and (ii) adsorbed AgNPs on titanium (Ti) substrates, a material widely used for implants (to test their effect against sessile bacteria). In both cases, the number of surviving cells was quantified. The small amount of Ag on the surface of Ti has an antimicrobial effect similar to that of pure Ag surfaces. We have also investigated the capability of AgNPs to kill planktonic bacteria and their cytotoxic effect on UMR-106 osteoblastic cells. The minimum bactericidal concentration found for both strains is much lower than the AgNP concentration that leads to cytotoxicity to osteoblasts. Planktonic P. aeruginosa show a higher susceptibility to Ag than S. aureus, which can be caused by the different wall structures, while for sessile bacteria, similar results are obtained for both strains. This can be explained by the presence of extracellular polymeric substances in the early stages of P. aeruginosa biofilm formation. Our findings can be important to improving the performance of Ti-based implants because a good bactericidal action is obtained with very small quantities of Ag, which are not detrimental to the cells involved in the osseointegration process. PMID:23534883

Flores, Constanza Y; Miñán, Alejandro G; Grillo, Claudia A; Salvarezza, Roberto C; Vericat, Carolina; Schilardi, Patricia L

2013-04-24

44

Facile synthesis of anisotropic silver nanoparticles and their surface-enhanced Raman scattering properties  

NASA Astrophysics Data System (ADS)

In this work, polyvinylpyrrolidone(PVP)-capped silver nanoparticles were synthesized using ethylene glycol as solvent and reducing agent through a simple, one-pot solvothermal method at 160 °C. UV-vis spectroscopy, TEM and Raman spectra are used to characterize the PVP-capped silver nanoparticles. The results show that the formed silver nanoparticles are anisotropy with different size and morphology such as triangle, hexagon and pentagon. Moreover, the formation process of silver nanoparticles was discussed in detail. Furthermore, the formed silver nanoparticles displayed high surface-enhanced Raman scattering effects.

Zhang, Danhui; Yang, Houbo

2014-02-01

45

Toxicity of silver nanoparticles–nanoparticle or silver ion?  

Microsoft Academic Search

The toxicity of silver nanoparticles (AgNPs) has been shown in many publications. Here we investigated to which degree the silver ion fraction of AgNP suspensions, contribute to the toxicity of AgNPs in A549 lung cells. Cell viability assays revealed that AgNP suspensions were more toxic when the initial silver ion fraction was higher. At 1.5?g\\/ml total silver, A549 cells exposed

Christiane Beer; Rasmus Foldbjerg; Yuya Hayashi; Duncan S. Sutherland; Herman Autrup

46

Antimicrobial Properties of Silver Nanoparticles  

NSDL National Science Digital Library

This module provides students the opportunity to "explore silver nanoparticles and their effectiveness against bacterial growth in hands-on laboratory activities." Students first make silver nanoparticles and then use them in an experiment they design. This lesson will require two or more class periods and is aimed at secondary students.The document is available to download in PDF file format.

Kouadio, Carrie; Muskin, Joe

2012-10-15

47

Biological synthesis of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Fungus-mediated synthesis of silver nanoparticles is reported. The nanosilver was formed in contact with the cell-free filtrate of Penicillium strain studied. The nanoparticles were characterized by means of the UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesized nanosilver showed a absorbed maximum at 425 nm in the visible region. The SEM characterization of the fungus cells treated with silver nitrite indicated that the protein might be responsible for the reduction of silver ions. Transmission electron microscopy (TEM) micrograph showed formation of silver nanoparticles in the range of 10-100 nm.

Maliszewska, I.; Szewczyk, K.; Waszak, K.

2009-01-01

48

Shaped gold and silver nanoparticles  

Microsoft Academic Search

Advance in the synthesis of shaped nanoparticles made of gold and silver is reviewed in this article. This review starts with\\u000a a new angle by analyzing the relationship between the geometrical symmetry of a nanoparticle shape and its internal crystalline\\u000a structures. According to the relationship, the nanoparticles with well-defined shapes are classified into three categories:\\u000a nanoparticles with single crystallinity, nanoparticles

Yugang Sun; Changhua An

2011-01-01

49

Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439 nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14 nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons.

Bindhu, M. R.; Sathe, V.; Umadevi, M.

2013-11-01

50

Multifunctional PLGA particles containing poly(l-glutamic acid)-capped silver nanoparticles and ascorbic acid with simultaneous antioxidative and prolonged antimicrobial activity.  

PubMed

A water-soluble antioxidant (ascorbic acid, vitamin C) was encapsulated together with poly(l-glutamic acid)-capped silver nanoparticles (AgNpPGA) within a poly(lactide-co-glycolide) (PLGA) polymeric matrix and their synergistic effects were studied. The PLGA/AgNpPGA/ascorbic acid particles synthesized by a physicochemical method with solvent/non-solvent systems are spherical, have a mean diameter of 775 nm and a narrow size distribution with a polydispersity index of 0.158. The encapsulation efficiency of AgNpPGA/ascorbic acid within PLGA was determined to be >90%. The entire amount of encapsulated ascorbic acid was released in 68 days, and the entire amount of AgNpPGAs was released in 87 days of degradation. The influence of PLGA/AgNpPGA/ascorbic acid on cell viability, generation of reactive oxygen species (ROS) in HepG2 cells, as well as antimicrobial activity against seven different pathogens was investigated. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay indicated good biocompatibility of these PLGA/AgNpPGA/ascorbic acid particles. We measured the kinetics of ROS formation in HepG2 cells by a DCFH-DA assay, and found that PLGA/AgNpPGA/ascorbic acid caused a significant decrease in DCF fluorescence intensity, which was 2-fold lower than that in control cells after a 5h exposure. This indicates that the PLGA/AgNpPGA/ascorbic acid microspheres either act as scavengers of intracellular ROS and/or reduce their formation. Also, the results of antimicrobial activity of PLGA/AgNpPGA/ascorbic acid obtained by the broth microdilution method showed superior and extended activity of these particles. The samples were characterized using Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, zeta potential and particle size analysis. This paper presents a new approach to the treatment of infection that at the same time offers a very pronounced antioxidant effect. PMID:23988864

Stevanovi?, Magdalena; Bra?ko, Ines; Milenkovi?, Marina; Filipovi?, Nenad; Nuni?, Jana; Filipi?, Metka; Uskokovi?, Dragan P

2014-01-01

51

Malva parviflora extract assisted green synthesis of silver nanoparticles.  

PubMed

Five plant leaf extracts (Malva parviflora, Beta vulgaris subsp. Vulgaris, Anethum graveolens, Allium kurrat and Capsicum frutescens) were screened for their bioreduction behavior for synthesis of silver nanoparticles. M. parviflora (Malvaceae) was found to exhibit the best reducing and protecting action in terms of synthesis rate and monodispersity of the prepared silver nanoparticles. Our measurements indicate that biosynthesis of Ag nanoparticles by M. parviflora produces Ag nanoparticles with the diameters in the range of 19-25 nm. XRD studies reveal a high degree of crystallinity and monophasic Ag nanoparticles of face-centered cubic structure. FTIR analysis proved that particles are reduced and stabilized in solution by the capping agent that is likely to be proteins secreted by the biomass. The present process is an excellent candidate for the synthesis of silver nanoparticles that is simple, easy to perform, pollutant free and inexpensive. PMID:23010627

Zayed, Mervat F; Eisa, Wael H; Shabaka, A A

2012-12-01

52

Malva parviflora extract assisted green synthesis of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Five plant leaf extracts (Malva parviflora, Beta vulgaris subsp. Vulgaris, Anethum graveolens, Allium kurrat and Capsicum frutescens) were screened for their bioreduction behavior for synthesis of silver nanoparticles. M. parviflora (Malvaceae) was found to exhibit the best reducing and protecting action in terms of synthesis rate and monodispersity of the prepared silver nanoparticles. Our measurements indicate that biosynthesis of Ag nanoparticles by M. parviflora produces Ag nanoparticles with the diameters in the range of 19-25 nm. XRD studies reveal a high degree of crystallinity and monophasic Ag nanoparticles of face-centered cubic structure. FTIR analysis proved that particles are reduced and stabilized in solution by the capping agent that is likely to be proteins secreted by the biomass. The present process is an excellent candidate for the synthesis of silver nanoparticles that is simple, easy to perform, pollutant free and inexpensive.

Zayed, Mervat F.; Eisa, Wael H.; Shabaka, A. A.

2012-12-01

53

Synthesis of silver nanoparticles by electron irradiation of silver acetate  

NASA Astrophysics Data System (ADS)

A novel and facile route to synthesize crystalline silver nanoparticles is presented, which is based on electron irradiation technique. Only by irradiating an electron beam onto silver acetate precursor material, silver nanocrystals with the sizes of 15-40 nm were synthesized. The morphology and chemical composition of the irradiated samples were characterized by SEM, TEM, XRD and EELS. The precursor material was decomposed by the energetic electrons and consequently the chemical composition of the material was changed. As the electron fluence was gradually increased, the precursor was converted to silver (I) oxide and finally into silver nanocrystals. Thus, besides silver nanoparticles, silver oxide film can also be synthesized using the electron irradiation technique by controlling the electron fluence. The technique can be useful for mass production of silver nanoparticles and for patterned silver nanoparticle film.

Li, Yue; Kim, Yong Nam; Lee, Eun Je; Cai, Wei Ping; Cho, Sung Oh

2006-10-01

54

Subchronic oral toxicity of silver nanoparticles  

Microsoft Academic Search

BACKGROUND: The antibacterial effect of silver nanoparticles has resulted in their extensive application in health, electronic, consumer, medicinal, pesticide, and home products; however, silver nanoparticles remain a controversial area of research with respect to their toxicity in biological and ecological systems. RESULTS: This study tested the oral toxicity of silver nanoparticles (56 nm) over a period of 13 weeks (90

Yong Soon Kim; Moon Yong Song; Jung Duck Park; Kyung Seuk Song; Hyeon Ryol Ryu; Yong Hyun Chung; Hee Kyung Chang; Ji Hyun Lee; Kyung Hui Oh; Bruce J Kelman; In Koo Hwang; Il Je Yu

2010-01-01

55

Silver Nanoparticles from Ultrasonic Spray Pyrolysis of Aqueous Silver Nitrate  

Microsoft Academic Search

Silver particles less than 20 nm in diameter were synthesized by pyrolysis of an ultrasonically atomized spray of highly dilute aqueous silver nitrate solution at temperatures above 650°C and below the melting point of silver. Feed solution concentration and ultrasound power applied to the atomizer were found to have a significant impact on the particle size of the silver nanoparticles.

Kalyana C. Pingali; David A. Rockstraw; Shuguang Deng

2005-01-01

56

Antituberculous effect of silver nanoparticles  

NASA Astrophysics Data System (ADS)

The in vitro experiment, involving 1164 strains of the tuberculosis mycobacteria, exhibited a potentiating effect of silver nanoparticles on known antituberculous preparations in respect of overcoming drug-resistance of the causative agent. The in vitro experiment, based on the model of resistant tuberculosis, was performed on 65 white mice. An evident antituberculous effect of the nanocomposite on the basis of silver nanoparticles and isoniazid was proved. Toxicological assessment of the of nanopreparations was carried out. The performed research scientifically establishes efficacy and safety of the nanocomposite application in combination therapy of patients suffering from drug-resistant tuberculosis.

Kreytsberg, G. N.; Gracheva, I. E.; Kibrik, B. S.; Golikov, I. V.

2011-04-01

57

LL37 peptide@silver nanoparticles: combining the best of the two worlds for skin infection control  

NASA Astrophysics Data System (ADS)

Capping silver nanoparticles with LL37 peptide eradicates the antiproliferative effect of silver on primary skin cells, but retains the bactericidal properties of silver nanoparticles with activities comparable to silver nitrate or silver sulfadiazine. In addition, LL37 capped silver nanoparticles have anti-biofilm formation activity.Capping silver nanoparticles with LL37 peptide eradicates the antiproliferative effect of silver on primary skin cells, but retains the bactericidal properties of silver nanoparticles with activities comparable to silver nitrate or silver sulfadiazine. In addition, LL37 capped silver nanoparticles have anti-biofilm formation activity. Electronic supplementary information (ESI) available: Changes on AgNP-SPB absorption; changes on AgNP-SPB as A/A0 measured in LB or DMEM media; number of survival colonies in the presence of LL37; human skin fibroblasts cell toxicity in the presence of different silver sources measured using MTS assay; effect of LL37@AgNP on the proliferation profile of human skin fibroblasts; effect of AgSD and AgNO3 on the proliferation profile of human skin fibroblasts in the presence of LL37 peptide; representative flow cytometry profiles for human skin fibroblasts stained with Alexa Fluor®488 annexin V/Dead cell apoptosis kit. See DOI: 10.1039/c4nr01284d

Vignoni, Mariana; de Alwis Weerasekera, Hasitha; Simpson, Madeline J.; Phopase, Jaywant; Mah, Thien-Fah; Griffith, May; Alarcon, Emilio I.; Scaiano, Juan C.

2014-05-01

58

Synthesis of biomacromolecule-stabilized silver nanoparticles and their surface-enhanced Raman scattering properties  

NASA Astrophysics Data System (ADS)

In this work, water soluble silver nanoparticles stabilized by biomacromolecule, were produced through using an aqueous solution of silver nitrate with Bovine Serum Albumin (BSA) under different reducing agents (such as sodium borohydride, hydrazine, N, N-dimethyl formamide) at the room temperature, where BSA provided the main function to form monodispersed silver nanoparticles. UV-vis spectroscopy, Fluorescence spectra, TEM and HR-TEM are used to characterize the BSA-capped silver nanoparticles under different condition. The results show that the formed silver nanoparticles have different size and morphology under the three different reducing agents. Moreover, the fluorescence intensity of BSA was drastically quenched in presence of Ag nanoparticles from the results of fluorescence spectra. Furthermore, the surface-enhanced Raman scattering effects of the formed silver nanoparticles were also displayed and we made a comparison under three different reducing agents.

Zhang, Danhui; Yang, Houbo

2013-09-01

59

Silver Nanoparticles Part 2: BDo Silver Nanoparticles Inhibit Bacterial Growth?  

NSDL National Science Digital Library

The NACK Center is an organization committed to supporting two âÂÂyear degree programs in micro and nanotechnology. The center offers online educational material for curriculum enhancement in this subject field. One of these resources is a lab documentation focusing on the topic of silver nanoparticles. The lab "may be used with a middle school through high school biology class.â The lesson includes objectives, sample solution preparations, and sample data and calculations. Overall, the objectives of this lesson are to practice aseptic techniques to inoculate/grow bacteria and describe the impact of silver nanoparticles on bacterial growth. The site requires a free log-in for access to the material.

2010-03-31

60

Temporal evolution of capped cadmium sulfide nanoparticles  

NASA Astrophysics Data System (ADS)

Cadmium sulfide nanoparticles capped with thioglycolic acid as an organic ligand were synthesized by solution chemistry. Temporal evolution was studied by optical absorption, fluorescence, TEM, FTIR and x-ray diffraction measurements to understand the growth and stability of nanocrystals/ligand composites. The results suggest that besides being a good capping agent, thioglycolic acid also acts as an effective passivating ligand for electronically active surface states of CdS nanoparticles. Such binding quenches surface recombination and improves excitonic (band-to-band) recombination. This makes CdS nanoparticles an attractive material for certain applications wherein surfaces states are to be eliminated.

Kalasad, M. N.; Rabinal, M. K.; Mulimani, B. G.; Avadhani, G. S.

2008-04-01

61

Using Silver Nanoparticles as an Antimicrobial Agent  

Microsoft Academic Search

\\u000a Antimicrobial and antifungal properties of silver nanoparticles, silver ions, acrylate paint and cotton fabric impregnated\\u000a with Ag nanoparticles were assessed against Escherichia coli (Gram-negative bacterium); Staphylococcus aureus and Bacillus subtilis (Gram-positive bacteria); Aspergillus niger, Aureobasidium pullulans and Penicillium phoeniceum (cosmopolitan saprotrophic fungi). The silver ions used in the bacterial susceptibility tests were released from pure silver\\u000a electrodes using a 12

R. R. Khaydarov; R. A. Khaydarov; S. Evgrafova; Y. Estrin

62

Supramolecular chirality of cysteine modified silver nanoparticles  

Microsoft Academic Search

Silver nanoparticles (?45nm) were prepared by citrate reduction of AgNO3 and modified with cysteine and N-, C- and S-protected cysteine derivatives. Based on interpretation of absorption and circular dichroism spectra in UV–Vis range, unusual chiral architecture of modified silver nanoparticles (independently on the cysteine enantiomer used) was uncovered. This phenomenon was observed even after modification of silver nanoparticles with racemate

Pavel ?ezanka; Kamil Záruba; Vladimír Král

2011-01-01

63

Preparation of New Reducing Agent for the Synthesis of Silver Nanoparticles  

NASA Astrophysics Data System (ADS)

2,3,5,6-Tetrakis-(morpholinomethyl)hydroquinone (TMMH) is used first time to prepare spherical silver nanoparticles by the reduction of Silver nitrate (AgNO3) in water-ethanol medium without using any stabilizing and capping agent. The compound (TMMH) was isolated by aminomethylation of hydroquinone with morpholine. The resultant compound characterized by 1H NMR, 13C NMR and FT-IR Spectra for conformation studies. The ratio of AgNO3 and compound (TMMH) played role in controlling the particle size and shape of silver nanoparticles. The formation of the silver nanoparticles was observed in UV-Vis absorption spectroscopy.

Manivel, P.; Sivashanmugan, K.; Viswanathan, C.; Mangalaraj, D.

2011-07-01

64

The effect of temperature on antibacterial activity of biosynthesized silver nanoparticles.  

PubMed

The purpose of this study was the evaluation of two different temperatures on antibacterial activity of the biosynthesized silver nanoparticles. 38 silver nanoparticles-producing bacteria were isolated from soil and identified. Biosynthesis of silver nanoparticles by these bacteria was verified through visible light spectrophotometry. Two strains were relatively active for production of silver nanoparticles. These strains were subjected for molecular identification and recognized as Bacillus sp. and Acinetobacter schindleri. In the present study, the effect of temperatures was evaluated on structure and antimicrobial properties of the silver nanoparrticles by transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and antimicrobial Agar well diffusion methods. The silver nanoparticles showed antibacterial activity against all the pathogenic bacteria; however, this property was lost after treatment of the silver nanoparticles by high temperatures (100 and 300 °C). TEM images showed that the average sizes of heated silver nanoparticles were >100 nm. However, these were <100 nm for non-heated silver nanoparticles. Although, XRD patterns showed the crystalline structure of heated silver nanoparticles, their antibacterial activities were less. This was possible because of the sizes and accordingly less penetration of the particles into the bacterial cells. In addition, elimination of the capping agents by heat might be considered another reason. PMID:23324852

Pourali, Parastoo; Baserisalehi, Majid; Afsharnezhad, Sima; Behravan, Javad; Ganjali, Rashin; Bahador, Nima; Arabzadeh, Sepideh

2013-02-01

65

Coleus aromaticus leaf extract mediated synthesis of silver nanoparticles and its bactericidal activity  

NASA Astrophysics Data System (ADS)

The utilization of various plant resources for the biosynthesis of metallic nanoparticles is called green nanotechnology, and it does not utilize any harmful chemical protocols. The present study reports the plant-mediated synthesis of silver nanoparticles using the plant leaf extract of Coleus aromaticus, which acts as a reducing and capping agent. The silver nanoparticles were characterized by ultraviolet visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and the size of the silver nanoparticles is 44 nm. The bactericidal activity of the silver nanoparticles was carried out by disc diffusion method that showed high toxicity against Bacillus subtilis and Klebsiella planticola. Biosynthesis of silver nanoparticles by using plant resources is an eco-friendly, reliable process and suitable for large-scale production. Moreover, it is easy to handle and a rapid process when compared to chemical, physical, and microbe-mediated synthesis process.

Vanaja, Mahendran; Annadurai, Gurusamy

2013-06-01

66

Efficient synthesis of silver nanoparticles from Prosopis juliflora leaf extract and its antimicrobial activity using sewage  

NASA Astrophysics Data System (ADS)

In this paper, aqueous extract of fresh leaves of Prosopis juliflora was used for the synthesis of silver (Ag) nanoparticles. UV-Vis spectroscopy studies were carried out to asses silver nanoparticles formation within 5 min, scanning electron microscopic was used to characterize shape of the Ag nanoparticles, X-ray diffraction analysis confirms the nanoparticles as crystalline silver and facecentered cubic type and Fourier transform infra-red assed that shows biomolecule compounds which are responsible for reduction and capping material of silver nanoparticles. The anti microbial activity of silver nanoparticle was performed using sewage. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods.

Raja, K.; Saravanakumar, A.; Vijayakumar, R.

2012-11-01

67

Interaction of silver nanoparticles with HIV-1  

PubMed Central

The interaction of nanoparticles with biomolecules and microorganisms is an expanding field of research. Within this field, an area that has been largely unexplored is the interaction of metal nanoparticles with viruses. In this work, we demonstrate that silver nanoparticles undergo a size-dependent interaction with HIV-1, with nanoparticles exclusively in the range of 1–10 nm attached to the virus. The regular spatial arrangement of the attached nanoparticles, the center-to-center distance between nanoparticles, and the fact that the exposed sulfur-bearing residues of the glycoprotein knobs would be attractive sites for nanoparticle interaction suggest that silver nanoparticles interact with the HIV-1 virus via preferential binding to the gp120 glycoprotein knobs. Due to this interaction, silver nanoparticles inhibit the virus from binding to host cells, as demonstrated in vitro.

Elechiguerra, Jose Luis; Burt, Justin L; Morones, Jose R; Camacho-Bragado, Alejandra; Gao, Xiaoxia; Lara, Humberto H; Yacaman, Miguel Jose

2005-01-01

68

Amorphous silicon coatings with silver nanoparticles  

NASA Astrophysics Data System (ADS)

We describe a plasma-ion sputtering technology for obtaining amorphous silicon coatings containing dispersed silver nanoparticles with average dimensions of 20-30 nm. Results of X-ray diffraction and electron-microscopic investigations of these coatings are presented, and a possible mechanism of silver nano-particle formation from 2- to 3-nm-sized nanoclusters is considered.

Tuleushev, Yu. Zh.; Volodin, V. N.; Zhakanbaev, E. A.; Zdorovets, M. V.

2013-11-01

69

Interaction of silver nanoparticles with Tacaribe virus  

Microsoft Academic Search

ABSTRACT: BACKGROUND: Silver nanoparticles possess many unique properties that make them attractive for use in biological applications. Recently they received attention when it was shown that 10 nm silver nanoparticles were bactericidal, which is promising in light of the growing number of antibiotic resistant bacteria. An area that has been largely unexplored is the interaction of nanomaterials with viruses and

Janice L Speshock; Richard C Murdock; Laura K Braydich-Stolle; Amanda M Schrand; Saber M Hussain

2010-01-01

70

Differential interaction of silver nanoparticles with cysteine  

Microsoft Academic Search

Understanding the characteristics of cysteine on a solid surface is an important issue in protein study and amino acid analysis. Therefore, cysteine was selected as a model biomolecule to study the interaction with plasmonic silver nanoparticles. In this study, we report the differential interaction of cysteine with silver nanoparticles synthesised by Lee and Meisel (using citrate as reductant), and modified

Aswathy Ravindran; Sindhu Priya Dhas; N. Chandrasekaran; Amitava Mukherjee

2012-01-01

71

Mycosynthesis and characterization of silver nanoparticles and their activity against some human pathogenic bacteria.  

PubMed

The aim of this study was to biosynthesis silver nanoparticles from the fungus Nigrospora sphaerica isolated from soil samples and to examine their activity against five human pathogenic strains of bacteria viz. Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi and Staphylococcus aureus using disc diffusion method. The synergistic effect of silver nanoparticles in combination with commonly used antibiotic Gentamycin against the selected bacteria was also examined. The synthesized silver nanoparticles from free-cell filtrate were characterized by using UV-Vis spectrophotometer analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). UV-Vis spectrophotometer analysis showed a peak at 420 nm indicating the synthesis of silver nanoparticles, FTIR analysis verified the detection of protein capping of silver nanoparticles while SEM micrographs revealed that the silver nanoparticles are dispersed and aggregated and mostly having spherical shape within the size range between 20 and 70 nm. The synthesized silver nanoparticles exhibited a varied growth inhibition activity (15-26 mm diam inhibition zones) against the tested pathogenic bacteria. A remarkable increase of bacterial growth inhibition (26-34 mm diam) was detected when a combination of silver nanoparticles and Gentamycin was used. A significant increase in fold area of antibacterial activity was observed when AgNPs in combination with Gentamycin was applied. The synthesized silver nanoparticles produced by the fungus N. sphaerica is a promising to be used as safe drug in medical therapy due to their broad spectrum against pathogenic bacteria. PMID:24627178

Muhsin, Tawfik M; Hachim, Ahmad K

2014-07-01

72

Immobilization of silver nanoparticles on polyethylene terephthalate  

PubMed Central

Two different procedures of grafting with silver nanoparticles (AgNP) of polyethylene terephthalate (PET), activated by plasma treatment, are studied. In the first procedure, the PET foil was grafted with biphenyl-4,4?-dithiol and subsequently with silver nanoparticles. In the second one, the PET foil was grafted with silver nanoparticles previously coated with the same dithiol. X-ray photoelectron spectroscopy and electrokinetic analysis were used for characterization of the polymer surface at different modification steps. Silver nanoparticles were characterized by ultraviolet-visible spectroscopy and by transmission electron microscopy (TEM). The first procedure was found to be more effective. It was proved that the dithiol was chemically bonded to the surface of the plasma-activated PET and that it mediates subsequent grafting of the silver nanoparticles. AgNP previously coated by dithiol bonded to the PET surface much less.

2014-01-01

73

Quenching dynamics promoted by silver nanoparticles  

Microsoft Academic Search

We have studied fluorescence quenching by electron transfer between tris(2,2?-bipyridyl)ruthenium(II) complex and methyl viologen in solutions containing silver nanoparticles. The Stern–Volmer plot and transient absorbance indicate that both dynamic and static mechanisms are involved in the quenching. In the presence of silver nanoparticles, reverse saturable absorption at silver surfaces has promoted the quenching process by populating the excited triplet state

I-Yin Sandy Lee; Honoh Suzuki

2008-01-01

74

Investigation of size distribution of silver nanoparticles  

NASA Astrophysics Data System (ADS)

In this work, we present a physical methodology of preparing silver nanoparticles suspended in the deionized water. For this purpose, we apply the DC spark method and present the size distribution (by Zetasizer) and optical properties (by UV/VIS) of the nanoparticles in two different voltages. The obtained results using the DC spark method show that the fabrication of silver nanoparticles in deionized water without any surfactants and stabilizers is relatively cheap and pollution free. Using the method, we could prepare the silver nanoparticles smaller than 5 nm.

Khordad, R.; Vakili, M. R.; Bijanzadeh, A. R.

2012-02-01

75

Synthesis of gold and silver nanoparticles using leaf extract of Perilla frutescens--a biogenic approach.  

PubMed

The present investigation demonstrates a rapid biogenic approach for the synthesis of gold and silver nanoparticles using biologically active and medicinal important Perilla frutescens leaf extract as a reducing and stabilizing agent under ambient conditions. Gold and silver nanoparticles were first synthesized from Perilla frutescens leaf extract which was used as a vegetable and in traditional medicines for a long time in Korea, Japan, and China. The nanoparticles obtained were characterized by UV-vis spectroscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Surface plasmon resonance spectra of gold and silver nanoparticles were obtained at 540 and 430 nm and triangular and spherical shape respectively. TEM studies showed that the particle sizes of gold and silver nanoparticles ranges -50 nm and -40 nm respectively. X-ray diffraction studies confirm that the biosynthesized nanoparticles were crystalline gold and silver. Fourier transform infra-red spectroscopy revealed that biomolecules were involved in the synthesis and capping of the nanoparticles produced. XRD and EDX confirmed the formation of gold and silver nanoparticles. This is a simple, efficient and rapid method to synthesize gold and silver nanoparticles at room temperature without use of toxic chemicals. Obtained gold and silver nanoparticles can be used in various biomedical and biotechnological applications. PMID:24738399

Basavegowda, Nagaraj; Lee, Yong Rok

2014-06-01

76

Photoemission electron microscopy of a plasmonic silver nanoparticle trimer  

NASA Astrophysics Data System (ADS)

We present a combined experimental and theoretical study to investigate the spatial distribution of photoelectrons emitted from silver-coated polystyrene nanoparticles. We use two-photon photoemission electron microscopy (2P-PEEM) to image electron emission from a silver-capped aggregate trimer. Finite difference time domain (FDTD) simulations are performed to model the intensity distributions of the electromagnetic near fields resulting from femtosecond laser excitation of localized surface plasmon oscillations in the trimer structure. We demonstrate that the predicted FDTD near-field intensity distribution reproduces the 2P-PEEM photoemission pattern.

Peppernick, Samuel J.; Joly, Alan G.; Beck, Kenneth M.; Hess, Wayne P.; Wang, Jinyong; Wang, Yi-Chung; Wei, W. David

2013-07-01

77

Biosynthesis of iron and silver nanoparticles at room temperature using aqueous sorghum bran extracts.  

PubMed

Iron and silver nanoparticles were synthesized using a rapid, single step, and completely green biosynthetic method employing aqueous sorghum extracts as both the reducing and capping agent. Silver ions were rapidly reduced by the aqueous sorghum bran extracts, leading to the formation of highly crystalline silver nanoparticles with an average diameter of 10 nm. The diffraction peaks were indexed to the face-centered cubic (fcc) phase of silver. The absorption spectra of colloidal silver nanoparticles showed a surface plasmon resonance (SPR) peak centered at a wavelength of 390 nm. Amorphous iron nanoparticles with an average diameter of 50 nm were formed instantaneously under ambient conditions. The reactivity of iron nanoparticles was tested by the H(2)O(2)-catalyzed degradation of bromothymol blue as a model organic contaminant. PMID:21133391

Njagi, Eric C; Huang, Hui; Stafford, Lisa; Genuino, Homer; Galindo, Hugo M; Collins, John B; Hoag, George E; Suib, Steven L

2011-01-01

78

Starch-directed green synthesis, characterization and morphology of silver nanoparticles.  

PubMed

Silver nanoparticles were prepared by a simple chemical reduction method using ascorbic acid and starch as reducing and stabilizing agents, respectively. The effect of starch, silver ions and ascorbic acid was studied on the morphology of the silver nano-particles using UV-visible spectrophotometry. The initial reaction time min and amount of starch were important parameters for the growth of Ag-nanoparticles. The morphology was evaluated from transmission electron microscopy (TEM). The truncated triangle nano-plates (from 17 to 30 nm), polyhedron, spherical with some irregular shaped Ag-nanoparticles were formed in presence of starch. Particles are aggregated in an irregular manner, leads to the formation of butterfly-like structures of silver. Starch acts as a stabilizing, shape-directing and capping agent during the growth processes. Silver nanoparticles adsorbed electrostatically on the outer OH groups of amylose left-handed helical conformation in solution. PMID:23104028

Khan, Zaheer; Singh, Taruna; Hussain, Javed Ijaz; Obaid, Abdullah Yousif; Al-Thabaiti, Shaeel Ahmed; El-Mossalamy, E H

2013-02-01

79

Glutathione promoted expeditious green synthesis of silver nanoparticles in water using microwaves  

EPA Science Inventory

Silver nanoparticles with size range 5-10 nm has been synthesized under microwave irradiation conditions using gluathione, an absolutely benign antioxidant that serves as the reducing as well as capping agent in aqueous medium. This rapid protocol yields the nanoparticles within ...

80

Green synthesis of silver nanoparticles using marine macroalga Chaetomorpha linum  

NASA Astrophysics Data System (ADS)

The present investigation demonstrates the formation of silver nanoparticles by the reduction of the aqueous silver metal ions during exposure to the seaweed ( Chaetomorpha linum) extract . The silver nanoparticles obtained were characterized by UV-visible spectrum, FTIR and scanning electron microscopy. The characteristic absorption peak at 422 nm in UV-vis spectrum confirmed the formation of silver nanoparticles. The colour intensity at 422 nm increased with duration of incubation. The size of nanoparticles synthesized varied from 3 to 44 nm with average of ~30 nm. The FTIR spectrum of C. linum extract showed peaks at 1,020, 1,112, 1,325, 1,512, 1,535, 1,610, 1,725, 1,862, 2,924, 3,330 cm-1. The vibrational bands corresponding to the bonds such as -C=C (ring), -C-O, -C-O-C and C=C (chain) are derived from water-soluble compounds such as amines, peptides, flavonoids and terpenoids present in C. linum extract. Hence, it may be inferred that these biomolecules are responsible for capping and efficient stabilization. Since no synthetic reagents were used in this investigation, it is environmentally safe and have potential for application in biomedicine and agriculture.

Kannan, R. Ragupathi Raja; Arumugam, R.; Ramya, D.; Manivannan, K.; Anantharaman, P.

2013-06-01

81

Nanosecond laser ablation of silver nanoparticle film  

NASA Astrophysics Data System (ADS)

Nanosecond laser ablation of polyvinylpyrrolidone (PVP) protected silver nanoparticle (20 nm diameter) film is studied using a frequency doubled Nd:YAG nanosecond laser (532 nm wavelength, 6 ns full width half maximum pulse width). In the sintered silver nanoparticle film, absorbed light energy conducts well through the sintered porous structure, resulting in ablation craters of a porous dome shape or crown shape depending on the irradiation fluence due to the sudden vaporization of the PVP. In the unsintered silver nanoparticle film, the ablation crater with a clean edge profile is formed and many coalesced nanoparticles of 50 to 100 nm in size are observed inside the ablation crater. These results and an order of magnitude analysis indicate that the absorbed thermal energy is confined within the nanoparticles, causing melting of nanoparticles and their coalescence to larger agglomerates, which are removed following melting and subsequent partial vaporization.

Chung, Jaewon; Han, Sewoon; Lee, Daeho; Ahn, Sanghoon; Grigoropoulos, Costas P.; Moon, Jooho; Ko, Seung H.

2013-02-01

82

Cytotoxic Potential of Silver Nanoparticles  

PubMed Central

Silver nanoparticles (AgNPs) have been widely used in industrial, household, and healthcare-related products due to their excellent antimicrobial activity. With increased exposure of AgNPs to human beings, the risk of safety has attracted much attention from the public and scientists. In review of recent studies, we discuss the potential impact of AgNPs on individuals at the cell level. In detail, we highlight the main effects mediated by AgNPs on the cell, such as cell uptake and intracellular distribution, cytotoxicity, genotoxicity, and immunological responses, as well as some of the major factors that influence these effects in vivo and in vivo, such as dose, time, size, shape, surface chemistry, and cell type. At the end, we summarize the main influences on the cell and indicate the challenges in this field, which may be helpful for assessing the risk of AgNPs in future.

Zhang, Tianlu; Wang, Liming

2014-01-01

83

Coupled plasmons induce broadband circular dichroism in patternable films of silver nanoparticles with chiral ligands  

NASA Astrophysics Data System (ADS)

This contribution reports the chiro-optic response of as-cast and photopatterned films of silver nanoparticles capped with photothermally-cleavable chiral ligands. We demonstrate broadband circular dichroism in these nanoparticle films, which is not present in dispersions of the nanoparticles capped with the chiral ligands. Long wavelength circular dichroism is derived from coupling of the plasmonic bands of neighbouring silver nanoparticles. Furthermore, the chiral response is preserved in the microstructured film after photopatterning using direct two-photon absorption in the plasmonic band of the silver nanoparticles. Thus, both the as-cast and photopatterned films show circular dichroism from the UV wavelength of intrinsic absorption of the ligand, through the plasmon resonances of both the isolated silver nanoparticles and the interacting nanoparticles, which extend to the near IR. Density functional theory (DFT) calculations of model electronic complexes of a chiral ligand and a small metallic cluster suggest that the new chiral bands at the plasmonic resonances are derived from new chiral hybrid electronic states of the metal nanoparticle-ligand complexes.This contribution reports the chiro-optic response of as-cast and photopatterned films of silver nanoparticles capped with photothermally-cleavable chiral ligands. We demonstrate broadband circular dichroism in these nanoparticle films, which is not present in dispersions of the nanoparticles capped with the chiral ligands. Long wavelength circular dichroism is derived from coupling of the plasmonic bands of neighbouring silver nanoparticles. Furthermore, the chiral response is preserved in the microstructured film after photopatterning using direct two-photon absorption in the plasmonic band of the silver nanoparticles. Thus, both the as-cast and photopatterned films show circular dichroism from the UV wavelength of intrinsic absorption of the ligand, through the plasmon resonances of both the isolated silver nanoparticles and the interacting nanoparticles, which extend to the near IR. Density functional theory (DFT) calculations of model electronic complexes of a chiral ligand and a small metallic cluster suggest that the new chiral bands at the plasmonic resonances are derived from new chiral hybrid electronic states of the metal nanoparticle-ligand complexes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03244b

Vidal, Xavier; Kim, Won Jin; Baev, Alexander; Tokar, Valentyna; Jee, Hongsub; Swihart, Mark. T.; Prasad, Paras N.

2013-10-01

84

Bacterial tolerance to silver nanoparticles (SNPs): aeromonas punctata isolated from sewage environment.  

PubMed

Use of silver nanoparticles (SNPs) is increasing in a large number of consumer products. Thus, the possible build-up of the nanoparticles in the environment is becoming a major concern. Aeromonas punctata isolated from sewage showed tolerance to 200 ?g/ml SNPs. The growth kinetics data for A. punctata treated with nanoparticles were similar to those in the absence of nanoparticles. There was a reduction in the amount of exopolysaccharides (EPS) in bacterial culture supernatant after nanoparticle-supernatant interaction. EPS capping of the nanoparticles was confirmed by UV-visible, XRD and comparative FTIR analysis. The EPS-capped SNPs showed less toxicity to Escherichia coli, Staphylococcus aureus and Micrococcus luteus compared to the uncapped ones. The study suggests capping of nanoparticles by bacterially produced EPS as a probable physiological defense mechanism. PMID:21077112

Sudheer Khan, S; Bharath Kumar, E; Mukherjee, Amitava; Chandrasekaran, N

2011-04-01

85

Electrochemical solid-state phase transformations of silver nanoparticles.  

PubMed

Adenosine triphosphate (ATP)-capped silver nanoparticles (ATP-Ag NPs) were synthesized by reduction of AgNO(3) with borohydride in water with ATP as a capping ligand. The NPs obtained were characterized using transmission electron microscopy (TEM), UV-vis absorption spectroscopy, X-ray diffraction, and energy-dispersive X-ray analysis. A typical preparation produced ATP-Ag NPs with diameters of 4.5 ± 1.1 nm containing ~2800 Ag atoms and capped with 250 ATP capping ligands. The negatively charged ATP caps allow NP incorporation into layer-by-layer (LbL) films with poly(diallyldimethylammonium) chloride at thiol-modified Au electrode surfaces. Cyclic voltammetry in a single-layer LbL film of NPs showed a chemically reversible oxidation of Ag NPs to silver halide NPs in aqueous halide solutions and to Ag(2)O NPs in aqueous hydroxide solutions. TEM confirmed that this takes place via a redox-driven solid-state phase transformation. The charge for these nontopotactic phase transformations corresponded to a one-electron redox process per Ag atom in the NP, indicating complete oxidation and reduction of all Ag atoms in each NP during the electrochemical phase transformation. PMID:22385520

Singh, Poonam; Parent, Kate L; Buttry, Daniel A

2012-03-28

86

Silver nanoparticle applications and human health  

Microsoft Academic Search

Nanotechnology is rapidly growing with nanoparticles produced and utilized in a wide range of commercial products throughout the world. For example, silver nanoparticles (Ag NP) are used in electronics, bio-sensing, clothing, food industry, paints, sunscreens, cosmetics and medical devices. These broad applications, however, increase human exposure and thus the potential risk related to their short- and long-term toxicity. A large

Maqusood Ahamed; Mohamad S. AlSalhi; M. K. J. Siddiqui

2010-01-01

87

Extracellular biosynthesis of gold and silver nanoparticles using Krishna tulsi ( Ocimum sanctum) leaf  

NASA Astrophysics Data System (ADS)

Aqueous extract of Ocimum sanctum leaf is used as reducing agent for the environmentally friendly synthesis of gold and silver nanoparticles. The nanoparticles were characterized using UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. These methods allow the synthesis of hexagonal gold nanoparticles having size ?30 nm showing two surface plasmon resonance (SPR) bands by changing the relative concentration of HAuCl 4 and the extract. Broadening of SPR is observed at larger quantities of the extract possibly due to biosorption of gold ions. Silver nanoparticles with size in the range 10-20 nm having symmetric SPR band centered around 409 nm are obtained for the colloid synthesized at room temperature at a pH of 8. Crystallinity of the nanoparticles is confirmed from the XRD pattern. Biomolecules responsible for capping are different in gold and silver nanoparticles as evidenced by the FTIR spectra.

Philip, Daizy; Unni, C.

2011-05-01

88

Synthesis and applications of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Due to their unique properties, silver nanoparticles are used in a wide range of applications, like electronics, optics, catalysis, biology, etc. The preferred route for their preparation has been, and still is, the reduction of silver salts in solutions. While dedicated reducing agents, solvents, and dispersants are typically used in this approach, in some cases, the same additive (ex: polyols) may play multiple roles. Such dual-function additives are particularly interesting alternatives as they offer the possibility of replacing the undesirable reductants often used in conventional precipitation methods. In the current research, an environmentally friendly route to prepare stable concentrated aqueous dispersions of silver nanoparticles is investigated experimentally. It was found that Arabic gum, a well known stabilizing agent, can also rapidly and completely reduce Ag 2O to metallic silver in alkaline solutions (pH >12.0) and elevated temperature (65 °C). The average size of the silver nanoparticles could be tailored from 13 to 30 nm by varying the experimental conditions. To prepare stable metal colloids by chemical precipitation methods requires in most cases a high concentration of polymeric dispersants. Consequently, the particles are embedded in the organic matrix, which can not be removed without affecting the properties of the particles and/or the dispersion stability. This can have a negative effect in many applications. In this work, an enzymatic hydrolysis method for isolating the silver particles from dispersions containing high concentrations of polymer was identified. In addition, a chemical hydrolysis method yielding dispersed silver nanoparticles with low content of residual polymer for printable electronics applications is investigated. The low sintering temperature of silver nanoparticles and high electrical conductivity make them very attractive for the fabrication of conductive patterns especially for flexible electronic applications. In the final section of this thesis, the silver nanoparticles are deposited using inkjet printing technology with a Dimatix printer DMP -2831. Silver nanoparticles of 13 nm, 80 nm, and mixtures of the two sizes were used to evaluate the effect of particle size and size distribution on the electrical properties of sintered films. The silver layers deposited with a 'drop-on-demand' inkjet printer were heated at temperatures ranging from 125°C to 200°C. The small particles formed less resistive films at 125°C, while the larger ones provided better electrical conductivity above 150°C. The inks containing mixed small and large particles yielded the most conductive silver films over the entire investigated temperature range. A mechanism explaining these results is proposed based on the evolution of film microstructure with temperature.

Balantrapu, Krishna Chaitanya

89

Green synthesis of colloidal silver nanoparticles using natural rubber latex extracted from Hevea brasiliensis  

NASA Astrophysics Data System (ADS)

Colloidal silver nanoparticles were synthesized by an easy green method using thermal treatment of aqueous solutions of silver nitrate and natural rubber latex (NRL) extracted from Hevea brasiliensis. The UV-Vis spectra detected the characteristic surface plasmonic absorption band around 435 nm. Both NRL and AgNO 3 contents in the reaction medium have influence in the Ag nanoparticles formation. Lower AgNO 3 concentration led to decreased particle size. The silver nanoparticles presented diameters ranging from 2 nm to 100 nm and had spherical shape. The selected area electron diffraction (SAED) patterns indicated that the silver nanoparticles have face centered cubic (fcc) crystalline structure. FTIR spectra suggest that reduction of the silver ions are facilitated by their interaction with the amine groups from ammonia, which is used for conservation of the NRL, whereas the stability of the particles results from cis-isoprene binding onto the surface of nanoparticles. Therefore natural rubber latex extracted from H. brasiliensis can be employed in the preparation of stable aqueous dispersions of silver nanoparticles acting as a dispersing and/or capping agent. Moreover, this work provides a new method for the synthesis of silver nanoparticles that is simple, easy to perform, pollutant free and inexpensive.

Guidelli, Eder José; Ramos, Ana Paula; Zaniquelli, Maria Elisabete D.; Baffa, Oswaldo

2011-11-01

90

Silver nanoparticles with gelatin nanoshells: photochemical facile green synthesis and their antimicrobial activity  

Microsoft Academic Search

In the current study, a facile green synthesis of silver-gelatin core–shell nanostructures (spherical, spherical\\/cubic hybrid,\\u000a and cubic, DLS diameter: 4.1–6.9 nm) is reported via the wet chemical synthesis procedure. Sunlight-UV as an available reducing\\u000a agent cause mild reduction of silver ions into the silver nanoparticles (Ag-NPs). Gelatin protein, as an effective capping\\/shaping\\u000a agent, was used in the reaction to self-assemble silver

Ali Pourjavadi; Rouhollah Soleyman

91

Cytotoxicity and genotoxicity of biogenic silver nanoparticles  

NASA Astrophysics Data System (ADS)

Biogenic silver nanoparticles with 40.3 ± 3.5 nm size and negative surface charge (- 40 mV) were prepared with Fusarium oxysporum. The cytotoxicity of 3T3 cell and human lymphocyte were studied by a TaliTM image-based cytometer and the genotoxicity through Allium cepa and comet assay. The results of BioAg-w (washed) and BioAg-nw (unwashed) biogenic silver nanoparticles showed cytotoxicity exceeding 50 ?g/mL with no significant differences of response in 5 and 10 ?g/mL regarding viability. Results of genotoxicity at concentrations 5.0 and 10.0 ug/mL show some response, but at concentrations 0.5 and 1.0 ?g/mL the washed and unwashed silver nanoparticles did not present any effect. This in an important result since in tests with different bacteria species and strains, including resistant, MIC (minimal inhibitory concentration) had good answers at concentrations less than 1.9 ?g/mL. This work concludes that biogenic silver nanoparticles may be a promising option for antimicrobial use in the range where no cyto or genotoxic effect were observed. Furthermore, human cells were found to have a greater resistance to the toxic effects of silver nanoparticles in comparison with other cells.

Lima, R.; Feitosa, L. O.; Ballottin, D.; Marcato, P. D.; Tasic, L.; Durán, N.

2013-04-01

92

Genotoxic analysis of silver nanoparticles in Drosophila.  

PubMed

Health risk assessment of nanomaterials is an emergent field, genotoxicity being an important endpoint to be tested. Since in vivo studies offer many advantages, such as the study of the bioavailability of nanomaterials to sensitive target cells, we propose Drosophila as a useful model for the study of the toxic and genotoxic risks associated with nanoparticle exposure. In this work we have carried out a genotoxic evaluation of silver nanoparticles in Drosophila by using the wing somatic mutation and recombination test. This test is based on the principle that loss of heterozygosis and the corresponding expression of the suitable recessive markers, multiple wing hairs and flare-3, can lead to the formation of mutant clones in larval cells, which are expressed as mutant spots on the wings of adult flies. Silver nanoparticles were supplied to third instar larvae at concentrations ranging from 0.1-10 mM. The results showed that small but significant increases in the frequency of total spots were observed, thus indicating that silver nanoparticles were able to induce genotoxic activity in the wing spot assay of D. melanogaster, mainly via the induction of somatic recombination. These positive results obtained with silver nanoparticles contrast with the negative findings obtained when silver nitrate was tested. PMID:21039182

Demir, E?ref; Vales, Gerard; Kaya, Bülent; Creus, Amadeu; Marcos, Ricardo

2011-09-01

93

Circular dichroism study of chiral biomolecules conjugated with silver nanoparticles  

Microsoft Academic Search

Chiral biomolecules conjugated with silver nanoparticles were investigated by circular dichroism (CD) spectroscopy. Silver nanoparticles were prepared by the citrate reduction method and were characterized by UV spectroscopy and TEM. Conjugation of thiol group-containing biomolecules, such as cysteine, glutathione and penicillamine, with silver nanoparticles resulted in the generation of new characteristic CD signals in the region of 240-400 nm, whereas

Taihua Li; Hyun Gyu Park; Hee-Seung Lee; Seong-Ho Choi

2004-01-01

94

Honey mediated green synthesis of silver nanoparticles.  

PubMed

The paper reports the pH controlled synthesis of silver nanoparticles using honey as reducing and stabilizing agents. By adjusting the pH of the aqueous solution containing metal ions and honey, nanoparticles of various size could be obtained at room temperature. The nanoparticles were characterized by UV-visible, high-resolution TEM, XRD and FTIR measurements. The colloid obtained at a pH of 8.5 is found to consist of monodispersed and nearly spherical silver nanoparticles of size approximately 4 nm which is a significant advancement in biosynthesis. The high crystallinity with fcc phase is evidenced by clear lattice fringes in the high-resolution TEM image and peaks in the XRD pattern corresponding to (111), (200), (220), (311) and (222) planes. FTIR spectrum indicates that the nanoparticles are bound to protein through the carboxylate ion group. PMID:20060777

Philip, Daizy

2010-03-01

95

Honey mediated green synthesis of silver nanoparticles  

NASA Astrophysics Data System (ADS)

The paper reports the pH controlled synthesis of silver nanoparticles using honey as reducing and stabilizing agents. By adjusting the pH of the aqueous solution containing metal ions and honey, nanoparticles of various size could be obtained at room temperature. The nanoparticles were characterized by UV-visible, high-resolution TEM, XRD and FTIR measurements. The colloid obtained at a pH of 8.5 is found to consist of monodispersed and nearly spherical silver nanoparticles of size ˜4 nm which is a significant advancement in biosynthesis. The high crystallinity with fcc phase is evidenced by clear lattice fringes in the high-resolution TEM image and peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes. FTIR spectrum indicates that the nanoparticles are bound to protein through the carboxylate ion group.

Philip, Daizy

2010-03-01

96

Mechanism of growth of colloidal silver nanoparticles stabilized by polyvinyl pyrrolidone in ?-irradiated silver nitrate solution  

Microsoft Academic Search

Silver nanoparticles were prepared by using polyvinyl pyrrolidone (PVP) as a stabilizer and ?-irradiation. Transmission electron microscopy (TEM) results showed that both the amount and the molecular weight of PVP in the irradiated solution considerably affect the average size of the silver nanoparticles. The average size of the silver nanoparticles decreases with increasing the amount of PVP in the solution,

Hyeon Suk Shin; Hyun Jung Yang; Seung Bin Kim; Mu Sang Lee

2004-01-01

97

Antimicrobial activity of spherical silver nanoparticles prepared using a biocompatible macromolecular capping agent: evidence for induction of a greatly prolonged bacterial lag phase  

PubMed Central

Background We have evaluated the antimicrobial properties of Ag-based nanoparticles (Nps) using two solid phase bioassays and found that 10-20 ?L of 0.3-3 ?M keratin-stabilized Nps (depending on the starting bacterial concentration = CI) completely inhibited the growth of an equivalent volume of ca. 103 to 104 colony forming units per mL (CFU mL-1) Staphylococcus aureus, Salmonella Typhimurium, or Escherichia coli O157:H7 on solid surfaces. Even after one week at 37°C on solid media, no growth was observed. At lower Np concentrations (= [Np]s), visible colonies were observed but they eventually ceased growing. Results To further study the physiology of this growth inhibition, we repeated these experiments in liquid phase by observing microbial growth via optical density at 590 nm (OD) at 37°C in the presence of a [Np] = 0 to 10-6 M. To extract various growth parameters we fit all OD[t] data to a common sigmoidal function which provides measures of the beginning and final OD values, a first-order rate constant (k), as well as the time to calculated 1/2-maximal OD (tm) which is a function of CI, k, as well as the microbiological lag time (T). Performing such experiments using a 96-well microtitre plate reader, we found that growth always occurred in solution but tm varied between 7 (controls; CI = 8 × 103 CFU mL-1) and > 20 hrs using either the citrate-([Np] ~ 3 × 10-7 M) or keratin-based ([Np] ~ 10-6 M) Nps and observed that {?tm/? [Np]}citrate ~ 5 × 107 and {?tm/? [Np]}keratin ~ 107 hr·L mol-1. We also found that there was little effect of Nps on S. aureus growth rates which varied only between k = 1.0 and 1.2 hr-1 (1.1 ± 0.075 hr-1). To test the idea that the Nps were changing the initial concentration (CI) of bacteria (i.e., cell death), we performed probabilistic calculations assuming that the perturbations in tm were due to CI alone. We found that such large perturbations in tm could only come about at a CI where the probability of any growth at all was small. This result indicates that much of the Np-induced change in tm was due to a greatly increased T (e.g., from ca. 1 to 15-20 hrs). For the solid phase assays we hypothesize that the bacteria eventually became non-culturable since they were inhibited from undergoing further cell division (T > many days). Conclusion We propose that the difference between the solid and liquid system relates to the obvious difference in the exposure, or residence, time of the Nps with respect to the bacterial cell membrane inasmuch as when small, Np-inhibited colonies were selected and streaked on fresh (i.e., no Nps present) media, growth proceeded normally: e.g., a small, growth-inhibited colony resulted in a plateful of typical S. aureus colonies when streaked on fresh, solid media.

2010-01-01

98

Silver nanoparticles enhance Pseudomonas aeruginosa PAO1 biofilm detachment.  

PubMed

Abstract Objectives: Silver nanoparticles (AgNPs) with a size ranging from 7 to 70?nm were synthesized using the ascorbic acid-citrate seed-mediated growth approach at room temperature. Methods: The 8?nm silver particles were prepared using gallic acid in alkaline conditions and used as seed to prepare AgNPs. Results: The presence of ascorbic acid and citrate allows the regulation of size and size distribution of the nanoparticles. The increase in free silver ion-to-seed ratio (Ag(+)/Ag(0)) resulted in changes of particle shape from spherical to pseudo-spherical and minor cylindrical shape. Further, a repetitive seeding approach resulted in the formation of pseudo-spherical particles with higher polydispersity index and minor distributions of tetrahedral particles. Citrate-capped AgNPs were stable and did not agglomerate upon centrifugation. The effect of AgNPs on biofilm reduction was evaluated using static culture on 96-well microtiter plates. Results showed that AgNPs with the smallest average diameter were most effective in the reduction of Pseudomonas aeruginosa biofilm colonies, which accounted for 90% of removal. Conclusion: The biofilm removal activities of the nanoparticles were found to be concentration-independent particularly for the concentration within the range of 80-200?µg/mL. PMID:23594297

Loo, Ching-Yee; Young, Paul M; Cavaliere, Rosalia; Whitchurch, Cynthia B; Lee, Wing-Hin; Rohanizadeh, Ramin

2014-06-01

99

Green synthesis of silver nanoparticles mediated by Pulicaria glutinosa extract  

PubMed Central

The green synthesis of metallic nanoparticles (NPs) has attracted tremendous attention in recent years because these protocols are low cost and more environmentally friendly than standard methods of synthesis. In this article, we report a simple and eco-friendly method for the synthesis of silver NPs using an aqueous solution of Pulicaria glutinosa plant extract as a bioreductant. The as-prepared silver NPs were characterized using ultraviolet–visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. Moreover, the effects of the concentration of the reductant (plant extract) and precursor solution (silver nitrate), the temperature on the morphology, and the kinetics of reaction were investigated. The results indicate that the size of the silver NPs varied as the plant extract concentration increased. The as-synthesized silver NPs were phase pure and well crystalline with a face-centered cubic structure. Further, Fourier-transform infrared spectroscopy analysis confirmed that the plant extract not only acted as a bioreductant but also functionalized the NPs’ surfaces to act as a capping ligand to stabilize them in the solvent. The developed eco-friendly method for the synthesis of NPs could prove a better substitute for the physical and chemical methods currently used to prepare metallic NPs commonly used in cosmetics, foods, and medicines.

Khan, Mujeeb; Khan, Merajuddin; Adil, Syed Farooq; Tahir, Muhammad Nawaz; Tremel, Wolfgang; Alkhathlan, Hamad Z; Al-Warthan, Abdulrahman; Siddiqui, Mohammed Rafiq H

2013-01-01

100

Antimicrobial active silver nanoparticles and silver\\/polystyrene core-shell nanoparticles prepared in room-temperature ionic liquid  

Microsoft Academic Search

Uniform silver nanoparticles and silver\\/polystyrene core-shell nanoparticles were successfully synthesized in a room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]·BF4). [BMIM]·BF4 plays a protective role to prevent the nanoparticles from aggregation during the preparation process. Transmission electron micrographs confirm that both silver nanoparticles and core-shell nanoparticles are regular spheres with the sizes in the range of 5–15 nm and 15–25 nm, respectively. The

Jing An; Desong Wang; Qingzhi Luo; Xiaoyan Yuan

2009-01-01

101

Hyaluronan- and heparin-reduced silver nanoparticles with antimicrobial properties  

PubMed Central

Aims Silver nanoparticles exhibit unique antibacterial properties that make these ideal candidates for biological and medical applications. We utilized a clean method involving a single synthetic step to prepare silver nanoparticles that exhibit antimicrobial activity. Materials & methods These nanoparticles were prepared by reducing silver nitrate with diaminopyridinylated heparin (DAPHP) and hyaluronan (HA) polysaccharides and tested for their efficacy in inhibiting microbial growth. Results & discussion The resulting silver nanoparticles exhibit potent antimicrobial activity against Staphylococcus aureus and modest activity against Escherichia coli. Silver–HA showed greater antimicrobial activity than silver–DAPHP, while silver–glucose nanoparticles exhibited very weak antimicrobial activity. Neither HA nor DAPHP showed activity against S. aureus or E. coli. Conclusion These results suggest that DAPHP and HA silver nanoparticles have potential in antimicrobial therapeutic applications.

Kemp, Melissa M; Kumar, Ashavani; Clement, Dylan; Ajayan, Pulickel; Mousa, Shaker

2009-01-01

102

Biofabrication of silver nanoparticles using Andrographis paniculata.  

PubMed

New and novel strategies are of recent interest in the development of silver nanoparticles. The plant extracts are eco-friendly, economical and cost effective for synthesis of nanoparticles. In this paper, we represent biofabrication of silver nanoparticles (AgNPs) using Andrographis paniculata and the synthesized AgNPs was monitored by ultra-violet visible spectroscopy (UV-Vis). The morphology and crystalline nature of AgNPs were determined from scanning electron microscopy (SEM) with Energy dispersive X-ray (EDX), X-ray diffraction patterns (XRD), Fourier transform-infrared spectroscopy (FT-IR). The size and the stability were detected by using Nanoparticle analyzer. The average size of the AgNPs was found to be 54 ± 2 nm and the Zeta potential was found to be -50.7 mV. The synthesized AgNPs have very good antifungal activity. PMID:24389508

Kotakadi, Venkata S; Gaddam, Susmila Aparna; Subba Rao, Y; Prasad, T N V K V; Varada Reddy, A; Sai Gopal, D V R

2014-02-12

103

Biosynthesis, Antimicrobial and Cytotoxic Effect of Silver Nanoparticles Using a Novel Nocardiopsis sp. MBRC-1  

PubMed Central

The biosynthesis of nanoparticles has been proposed as a cost effective environmental friendly alternative to chemical and physical methods. Microbial synthesis of nanoparticles is under exploration due to wide biomedical applications, research interest in nanotechnology and microbial biotechnology. In the present study, an ecofriendly process for the synthesis of nanoparticles using a novel Nocardiopsis sp. MBRC-1 has been attempted. We used culture supernatant of Nocardiopsis sp. MBRC-1 for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Nocardiopsis sp. MBRC-1 culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, FE-SEM, EDX, FTIR, and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 420?nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were spherical in shape with an average particle size of 45 ± 0.15?nm. The EDX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FTIR analysis revealed that the protein component in the form of enzyme nitrate reductase produced by the isolate in the culture supernatant may be responsible for reduction and as capping agents. The XRD spectrum showed the characteristic Bragg peaks of 1 2 3, 2 0 4, 0 4 3, 1 4 4, and 3 1 1 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against bacteria and fungi. Cytotoxicity of biosynthesized AgNPs against in vitro human cervical cancer cell line (HeLa) showed a dose-response activity. IC50 value was found to be 200??g/mL of AgNPs against HeLa cancer cells. Further studies are needed to elucidate the toxicity and the mechanism involved with antimicrobial and anticancer activity of the synthesized AgNPs as nanomedicine.

Manivasagan, Panchanathan; Senthilkumar, Kalimuthu; Sivakumar, Kannan; Kim, Se-Kwon

2013-01-01

104

Antimicrobial silver nanoparticles generated on cellulose nanocrystals  

Microsoft Academic Search

We describe a new approach to the formation of silver nanoparticles (Ag NPs) using cellulose nanocrystals. The process involves\\u000a periodate oxidation of cellulose nanocrystals, generating aldehyde functions which, in turn, are used to reduce Ag+ into Ag0 in mild alkaline conditions. The nanoparticles were characterized using transmission electron microscopy (TEM) and ultraviolet–visible\\u000a absorption spectroscopy. From the microscope studies (TEM) we

Nicolas DrogatRobert; Robert Granet; Vincent Sol; Abdelmajid Memmi; Naïma Saad; Carmen Klein Koerkamp; Philippe Bressollier; Pierre Krausz

2011-01-01

105

Photocatalytic degradation of methyl orange dye using silver (Ag) nanoparticles synthesized from Ulva lactuca.  

PubMed

In this paper, we report on biosynthesis of silver nanoparticles using Ulva lactuca (seaweed) at room temperature along with photocatalytic degradation of methyl orange dye. UV spectral analysis showed peak at 430 nm with special reference to the excitation of surfaces plasmon vibration by silver nanoparticles. FT-IR studies reveal the presence of bioactive functional groups such as phenolic compounds, amines and aromatic ring are found to be the capping and stabilizing agents of nanoparticles. The morphology of silver nanoparticles was found to be spherical and ranges about 48.59 nm as confirmed by HR-SEM. Negative zeta potential value of -34 mV suggests that the nanoparticles are highly stable in colloidal solution. XRD patterns also suggest the occurrence of spherical shaped particles due to the presence of silver ions. Further, photocatalytic degradation of methyl orange was measured spectrophotometrically by using silver as nanocatalyst under visible light illumination. The results revealed that biosynthesized silver nanoparticles using U. lactuca was found to be impressive in degrading methyl orange. PMID:23266074

Kumar, P; Govindaraju, M; Senthamilselvi, S; Premkumar, K

2013-03-01

106

Extracellular biosynthesis of silver nanoparticles using the fungus Fusarium semitectum  

SciTech Connect

Development of environmental friendly procedures for the synthesis of metal nanoparticles through biological processes is evolving into an important branch of nanobiotechnology. In this paper, we report on the use of fungus 'Fusarium semitectum' for the extracellular synthesis of silver nanoparticles from silver nitrate solution (i.e. through the reduction of Ag{sup +} to Ag{sup 0}). Highly stable and crystalline silver nanoparticles are produced in solution by treating the filtrate of the fungus F. semitectum with the aqueous silver nitrate solution. The formations of nanoparticles are understood from the UV-vis and X-ray diffraction studies. Transmission electron microscopy of the silver particles indicated that they ranged in size from 10 to 60 nm and are mostly spherical in shape. Interestingly the colloidal suspensions of silver nanoparticles are stable for many weeks. Possible medicinal applications of these silver nanoparticles are envisaged.

Basavaraja, S.; Balaji, S.D. [Department of Materials Science, Gulbarga University, Gulbarga 585106, Karnataka (India); Department of Chemistry, Gulbarga University, Gulbarga 585106, Karnataka (India); Lagashetty, Arunkumar [Appa Institute of Engineering and Technology, Gulbarga 585102, Karnataka (India); Rajasab, A.H. [Department of Botany, Gulbarga University, Gulbarga 585106, Karnataka (India); Venkataraman, A. [Department of Materials Science, Gulbarga University, Gulbarga 585106, Karnataka (India); Department of Chemistry, Gulbarga University, Gulbarga 585106, Karnataka (India)], E-mail: raman_chem@rediffmail.com

2008-05-06

107

Self-supported silver nanoparticles containing bacterial cellulose membranes  

Microsoft Academic Search

Hydrated bacterial cellulose (BC) membranes obtained from cultures of Acetobacter xylinum were used in the preparation of silver nanoparticles containing cellulose membranes. In situ preparation of Ag nanoparticles was achieved from the hydrolytic decomposition of silver triethanolamine (TEA) complexes. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns both lead to the observation of spherical metallic silver particles with

Hernane S. Barud; Celina Barrios; Thais Regiani; Rodrigo F. C. Marques; Marc Verelst; Jeannette Dexpert-Ghys; Younes Messaddeq; Sidney J. L. Ribeiro

2008-01-01

108

Synthesis of gold nanoparticles and silver nanoparticles via green technology  

NASA Astrophysics Data System (ADS)

The proposed work describes the comparison of various methods of green synthesis for preparation of Gold and Silver nanoparticles. Pure extracts of Lemon (Citrus limon) and Tomato (Solanum lycopersicum) were mixed with aqueous solution of auric tetrachloride and silver nitrate. The resultant solutions were treated with four common techniques to assist in the reduction namely photo catalytic, thermal, microwave assisted reduction and solvo - thermal reduction. UV - Visible Spectroscopy results and STM images of the final solutions confirmed the formation of stable metallic nanoparticles. A preliminary account of the green synthesis work is presented here.

Ahmed, Zulfiqaar; Balu, S. S.

2012-11-01

109

Size-Controlled and Optical Properties of Monodispersed Silver Nanoparticles Synthesized by the Radiolytic Reduction Method  

PubMed Central

Size-controlled and monodispersed silver nanoparticles were synthesized from an aqueous solution containing silver nitrate as a metal precursor, polyvinyl alcohol as a capping agent, isopropyl alcohol as hydrogen and hydroxyl radical scavengers, and deionized water as a solvent with a simple radiolytic method. The average particle size decreased with an increase in dose due to the domination of nucleation over ion association in the formation of the nanoparticles by gamma reduction. The silver nanoparticles exhibit a very sharp and strong absorption spectrum with the absorption maximum ?max blue shifting with an increased dose, owing to a decrease in particle size. The absorption spectra of silver nanoparticles of various particle sizes were also calculated using a quantum physics treatment and an agreement was obtained with the experimental absorption data. The results suggest that the absorption spectrum of silver nanoparticles possibly derived from the intra-band excitations of conduction electrons from the lowest energy state (n = 5, l = 0) to higher energy states (n ? 6; ?l = 0, ±1; ?s = 0, ±1), allowed by the quantum numbers principle. This demonstrates that the absorption phenomenon of metal nanoparticles based on a quantum physics description could be exploited to be added into the fundamentals of metal nanoparticles and the related fields of nanoscience and nanotechnology.

Saion, Elias; Gharibshahi, Elham; Naghavi, Kazem

2013-01-01

110

Inoculation of silicon nanoparticles with silver atoms  

PubMed Central

Silicon (Si) nanoparticles were coated inflight with silver (Ag) atoms using a novel method to prepare multicomponent heterostructured metal-semiconductor nanoparticles. Molecular dynamics (MD) computer simulations were employed, supported by high-resolution bright field (BF) transmission electron microscopy (HRTEM) and aberration-corrected scanning transmission electron microscopy (STEM) with a resolution ?0.1?nm in high angle annular dark field (HAADF) mode. These studies revealed that the alloying behavior and phase dynamics during the coating process are more complex than when attaching hetero-atoms to preformed nanoparticles. According to the MD simulations, Ag atoms condense, nucleate and diffuse into the liquid Si nanoparticles in a process that we term “inoculation”, and a phase transition begins. Subsequent solidification involves an intermediate alloying stage that enabled us to control the microstructure and crystallinity of the solidified hybrid heterostructured nanoparticles.

Cassidy, Cathal; Singh, Vidyadhar; Grammatikopoulos, Panagiotis; Djurabekova, Flyura; Nordlund, Kai; Sowwan, Mukhles

2013-01-01

111

Photochemical preparation of silver nanoparticles supported on zeolite crystals.  

PubMed

A facile and rapid photochemical method for preparing supported silver nanoparticles (Ag-NPs) in a suspension of faujasite type (FAU) zeolite nanocrystals is described. Silver cations are introduced by ion exchange into the zeolite and subsequently irradiated with a Xe-Hg lamp (200 W) in the presence of a photoactive reducing agent (2-hydroxy-2-methylpropiophenone). UV-vis characterization indicates that irradiation time and intensity (I0) influence significantly the amount of silver cations reduced. The full reduction of silver cations takes place after 60 s of a polychromatic irradiation, and a plasmon band of Ag-NPs appears at 380 nm. Transmission electron microscopy combined with theoretical calculation of the plasmon absorbance band using Mie theory shows that the Ag-NPs, stabilized in the micropores and on the external surface of the FAU zeolite nanocrystals, have an almost spheroidal shape with diameters of 0.75 and 1.12 nm, respectively. Ag-NPs, with a homogeneous distribution of size and morphology, embedded in a suspension of FAU zeolites are very stable (?8 months), even without stabilizers or capping agents. PMID:24810992

Zaarour, Moussa; El Roz, Mohamad; Dong, Biao; Retoux, Richard; Aad, Roy; Cardin, Julien; Dufour, Christian; Gourbilleau, Fabrice; Gilson, Jean-Pierre; Mintova, Svetlana

2014-06-01

112

Synthesis of silver nanoparticles and antibacterial property of silk fabrics treated by silver nanoparticles.  

PubMed

A silver nanoparticle solution was prepared in one step by mixing AgNO3 and a multi-amino compound (RSD-NH2) solution under ambient condition. RSD-NH2 was in-house synthesized by methacrylate and polyethylene polyamine in methanol, which has abundant amino and imino groups. However, the characterization of silver nanoparticles indicated that these nanoparticles are easy to agglomerate in solution. Therefore, an in situ synthesis method of silver nanoparticles on the silk fabrics was developed. The examined results confirmed that the in situ synthesized silver nanoparticles were evenly distributed on the surface of fibers. The inhibition zone test and the antibacterial rate demonstrated that the finished fabrics have an excellent antibacterial property against Staphylococcus aureus and Escherichia coli. Moreover, the nanosilver-treated silk fabrics were laundered 0, 5, 10, 20, and 50 times and still retained the exceptional antibacterial property. When the treated fabrics were washed 50 times, the antibacterial rate is more than 97.43% for S. aureus and 99.86% for E. coli. The excellent laundering durability may be attributed to the tight binding between silver nanoparticles and silk fibers through the in situ synthesis. This method provides an economic method to enhance the antibacterial capability of silk fabrics with good resistance to washings. PMID:24872803

Zhang, Guangyu; Liu, Yan; Gao, Xiaoliang; Chen, Yuyue

2014-01-01

113

Synthesis of silver nanoparticles and antibacterial property of silk fabrics treated by silver nanoparticles  

PubMed Central

A silver nanoparticle solution was prepared in one step by mixing AgNO3 and a multi-amino compound (RSD-NH2) solution under ambient condition. RSD-NH2 was in-house synthesized by methacrylate and polyethylene polyamine in methanol, which has abundant amino and imino groups. However, the characterization of silver nanoparticles indicated that these nanoparticles are easy to agglomerate in solution. Therefore, an in situ synthesis method of silver nanoparticles on the silk fabrics was developed. The examined results confirmed that the in situ synthesized silver nanoparticles were evenly distributed on the surface of fibers. The inhibition zone test and the antibacterial rate demonstrated that the finished fabrics have an excellent antibacterial property against Staphylococcus aureus and Escherichia coli. Moreover, the nanosilver-treated silk fabrics were laundered 0, 5, 10, 20, and 50 times and still retained the exceptional antibacterial property. When the treated fabrics were washed 50 times, the antibacterial rate is more than 97.43% for S. aureus and 99.86% for E. coli. The excellent laundering durability may be attributed to the tight binding between silver nanoparticles and silk fibers through the in situ synthesis. This method provides an economic method to enhance the antibacterial capability of silk fabrics with good resistance to washings.

2014-01-01

114

Synthesis of silver nanoparticles and antibacterial property of silk fabrics treated by silver nanoparticles  

NASA Astrophysics Data System (ADS)

A silver nanoparticle solution was prepared in one step by mixing AgNO3 and a multi-amino compound (RSD-NH2) solution under ambient condition. RSD-NH2 was in-house synthesized by methacrylate and polyethylene polyamine in methanol, which has abundant amino and imino groups. However, the characterization of silver nanoparticles indicated that these nanoparticles are easy to agglomerate in solution. Therefore, an in situ synthesis method of silver nanoparticles on the silk fabrics was developed. The examined results confirmed that the in situ synthesized silver nanoparticles were evenly distributed on the surface of fibers. The inhibition zone test and the antibacterial rate demonstrated that the finished fabrics have an excellent antibacterial property against Staphylococcus aureus and Escherichia coli. Moreover, the nanosilver-treated silk fabrics were laundered 0, 5, 10, 20, and 50 times and still retained the exceptional antibacterial property. When the treated fabrics were washed 50 times, the antibacterial rate is more than 97.43% for S. aureus and 99.86% for E. coli. The excellent laundering durability may be attributed to the tight binding between silver nanoparticles and silk fibers through the in situ synthesis. This method provides an economic method to enhance the antibacterial capability of silk fabrics with good resistance to washings.

Zhang, Guangyu; Liu, Yan; Gao, Xiaoliang; Chen, Yuyue

2014-05-01

115

Biosynthesis and structural characterization of silver nanoparticles from bacterial isolates  

SciTech Connect

Graphical abstract: In this study five bacterial isolates belong to different genera were found to be able to biosynthesize silver nanoparticles. Biosynthesis and spectral characterization are reported here. Highlights: {yields} About 300 bacterial isolates were screened for their ability to produce nanosilvers {yields} Five of them were potential candidates for synthesis of silver nanoparticles {yields} Production of silver nanoparticles was examined using UV-Vis, XRD, SEM and EDS. {yields} The presence of nanoparticles with all five bacterial isolates was confirmed. -- Abstract: This study aimed to develop a green process for biosynthesis of silver nanomaterials by some Egyptian bacterial isolates. This target was achieved by screening an in-house culture collection consists of 300 bacterial isolates for silver nanoparticle formation. Through screening process, it was observed that strains belonging to Escherichia coli (S30, S78), Bacillus megaterium (S52), Acinetobacter sp. (S7) and Stenotrophomonas maltophilia (S54) were potential candidates for synthesis of silver nanoparticles. The extracellular production of silver nanoparticles by positive isolates was investigated by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results demonstrated that UV-visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy micrograph showed formation of silver nanoparticles in the range of 15-50 nm. XRD-spectrum of the silver nanoparticles exhibited 2{theta} values corresponding to the silver nanocrystal that produce in hexagonal and cubic crystal configurations with different plane of orientation. In addition, the signals of the silver atoms were observed by EDS-spectrum analysis that confirms the presence of silver nanoparticles (AgNPs) in all positive bacterial isolates.

Zaki, Sahar, E-mail: saharzaki@yahoo.com [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt)] [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt); El Kady, M.F. [Fabrication Technology Department, Advanced Technology and New Materials Research Institute (ATNMRI), Mubarak City for Scientific Research and Technology Applications, Alexandria (Egypt)] [Fabrication Technology Department, Advanced Technology and New Materials Research Institute (ATNMRI), Mubarak City for Scientific Research and Technology Applications, Alexandria (Egypt); Abd-El-Haleem, Desouky [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt)] [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt)

2011-10-15

116

The role of silver nanoparticles on silver modified titanosilicate ETS10 in visible light photocatalysis  

Microsoft Academic Search

Nanoparticles of noble metals, such as silver and gold, have been investigated as one way to hinder the recombination of electrons and holes produced by irradiated semiconductors. However, the exact role silver plays in hindering electron–hole recombination is unclear. In order to assess the role of ionic silver, Ag+, and metallic silver, Ag0, on the potential photocatalytic activity of a

Zhaoxia Ji; Mariam N. Ismail; Dennis M. Callahan; Eko Pandowo; Zhuhua Cai; Trevor L. Goodrich; Katherine S. Ziemer; Juliusz Warzywoda; Albert Sacco

2011-01-01

117

Bioactivity of albumins bound to silver nanoparticles.  

PubMed

The last decade has witnessed a tremendous rise in the proposed applications of nanomaterials in the field of medicine due to their very attractive physiochemical properties and novel actions such as the ability to reach previously inaccessible targets such as brain. However biological activity of functional molecules bound to nanoparticles and its physiological consequences is still unclear and hence this area requires immediate attention. The functional properties of Human Serum Albumin (HSA) and Bovine Serum Albumin (BSA) bound to silver nanoparticles (~60 nm) have been studied under physiological environment. Esterase activity, binding of drugs (warfarin and ibuprofen), antioxidant activity and copper binding by albumins was evaluated. The catalytic efficiencies of HSA and BSA diminished upon binding to silver nanoparticles. Perturbation in binding of warfarin and ibuprofen, loss of free sulphydryls, antioxidant activity and enhancement of copper binding were observed in albumins bound to nanoparticles. These alterations in functional activity of nanoparticle bound albumins which will have important consequences should be taken into consideration while using nanoparticles for diagnostic and therapeutic purposes. PMID:24715529

Mariam, Jessy; Sivakami, S; Kothari, D C; Dongre, P M

2014-06-01

118

Shell crosslinked nanoparticles carrying silver antimicrobials as therapeutics†  

PubMed Central

Amphiphilic polymer nanoparticles loaded with silver cations or/and N-heterocyclic carbene–silver complexes were assessed as antimicrobial agents against Gram-negative pathogens Escherichia coli and Pseudomonas aeruginosa.

Li, Yali; Hindi, Khadijah; Watts, Kristin M.; Taylor, Jane B.; Zhang, Ke; Li, Zicheng

2010-01-01

119

Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution  

NASA Astrophysics Data System (ADS)

Silver nanoparticles are extensively used due to their chemical and physical properties and promising applications in areas such as medicine and electronics. Controlled synthesis of silver nanoparticles remains a major challenge due to the difficulty in producing long-term stable particles of the same size and shape in aqueous solution. To address this problem, we examine three strategies to stabilise aqueous solutions of 15 nm citrate-reduced silver nanoparticles using organic polymeric capping, bimetallic core-shell and bimetallic alloying. Our results show that these strategies drastically improve nanoparticle stability by distinct mechanisms. Additionally, we report a new role of polymer functionalisation in preventing further uncontrolled nanoparticle growth. For bimetallic nanoparticles, we attribute the presence of a higher valence metal on the surface of the nanoparticle as one of the key factors for improving their long-term stability. Stable silver-based nanoparticles, free of organic solvents, will have great potential for accelerating further environmental and nanotoxicity studies. PACS: 81.07.-b; 81.16.Be; 82.70.Dd.

Stevenson, Amadeus PZ; Blanco Bea, Duani; Civit, Sergi; Antoranz Contera, Sonia; Iglesias Cerveto, Alberto; Trigueros, Sonia

2012-02-01

120

Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution  

PubMed Central

Silver nanoparticles are extensively used due to their chemical and physical properties and promising applications in areas such as medicine and electronics. Controlled synthesis of silver nanoparticles remains a major challenge due to the difficulty in producing long-term stable particles of the same size and shape in aqueous solution. To address this problem, we examine three strategies to stabilise aqueous solutions of 15 nm citrate-reduced silver nanoparticles using organic polymeric capping, bimetallic core-shell and bimetallic alloying. Our results show that these strategies drastically improve nanoparticle stability by distinct mechanisms. Additionally, we report a new role of polymer functionalisation in preventing further uncontrolled nanoparticle growth. For bimetallic nanoparticles, we attribute the presence of a higher valence metal on the surface of the nanoparticle as one of the key factors for improving their long-term stability. Stable silver-based nanoparticles, free of organic solvents, will have great potential for accelerating further environmental and nanotoxicity studies. PACS: 81.07.-b; 81.16.Be; 82.70.Dd.

2012-01-01

121

A green approach for synthesis of gold and silver nanoparticles by Leishmania sp.  

PubMed

The application of microorganisms for the synthesis of metal nanoparticles as an eco-friendly and promising approach is ongoing. In this paper, an attempt has been made to investigate the capability of Leishmania sp. for synthesis of metal nanoparticles from aqueous silver and gold ions. The samples were analyzed by a UV-Vis spectroscopy and the results showed the absorbance peak values at 420 and 540 nm, respectively, for the surface plasmon resonance of silver and gold nanoparticles. The surface morphology of the nanoparticles in solution was visualized by atomic force microscope and scanning electron microscope images, which showed the production of metallic nanoparticles by this protozoan. Fourier transform infrared spectroscopy analyses confirmed the presence of different bands of protein as capping and stabilizing agent on the nanoparticles surfaces. The synthesized silver and gold nanoparticles were with dimensions ranging between 10 and 100 nm for silver and 50-100 nm for gold. These results of the present study have demonstrated the efficiency of this protozoan for synthesis of nanoparticles, by offering the merits of environmentally friendly, amenability, and time saving for large-scale production. PMID:23054815

Ramezani, Fatemeh; Jebali, Ali; Kazemi, Bahram

2012-11-01

122

The green synthesis, characterization and evaluation of the biological activities of silver nanoparticles synthesized from Iresine herbstii leaf aqueous extracts.  

PubMed

Silver has been used since time immemorial in different chemical form to treat burns, wounds and several infections caused by pathogenic bacteria. Advancement of biological process of nanoparticles synthesis is evolving into a key area of nanotechnology. The current study deals with the synthesis, characterization of silver nanoparticles using Iresine herbstii and evaluation of their antibacterial, antioxidant and cytotoxic activity. The reaction mixture turned to brownish gray color after 7 days of incubation and exhibits an absorbance peak around 460 nm characteristic of Ag nanoparticle. Scanning electron microscopy (SEM) and EDX analysis showed silver nanoparticles were pure and polydispersed and the size were ranging from 44 to 64 nm. X-ray diffraction (XRD) studies revealed that most of the nanoparticles were cubic and face centered cubic in shape. Fourier transform infrared spectroscopy (FTIR) showed nanoparticles were capped with plant compounds. Biosynthesized silver nanoparticles showed potent antibacterial activity against human pathogenic bacteria. Phytosynthesized nanoparticles exhibited strong antioxidant activity as well as cytotoxicity against HeLa cervical cell lines. The approach of green synthesis seems to be cost efficient, eco-friendly and easy alternative to conventional methods of silver nanoparticles synthesis. The powerful bioactivity demonstrated by the synthesized silver nanoparticles leads towards the clinical use as antibacterial, antioxidant as well as cytotoxic agent. PMID:22705935

Dipankar, C; Murugan, S

2012-10-01

123

Synergistic antibacterial effects of ?-lactam antibiotic combined with silver nanoparticles  

NASA Astrophysics Data System (ADS)

The bactericidal action of silver (0) nanoparticles and amoxicillin on Escherichia coli is studied, respectively. Increasing concentration of both amoxicillin (0-0.525 mg ml-1) and silver nanoparticles (0-40 µg ml-1) showed a higher antibacterial effect in Luria-Bertani (LB) medium. Escherichia coli cells have different bactericidal sensitivity to them. When amoxicillin and silver nanoparticles are combined, it results in greater bactericidal efficiency on Escherichia coli cells than when they were applied separately. Dynamic tests on bacterial growth indicated that exponential and stationary phases are greatly decreased and delayed in the synergistic effect of amoxicillin and silver nanoparticles. In addition, the effect induced by a preincubation with silver nanoparticles is examined. The results show that solutions with more silver nanoparticles have better antimicrobial effects. One hypothesized mechanism is proposed to explain this phenomenon.

Li, Ping; Li, Juan; Wu, Changzhu; Wu, Qingsheng; Li, Jian

2005-09-01

124

Enhanced thermal stability of phosphate capped magnetite nanoparticles  

NASA Astrophysics Data System (ADS)

We have studied the effect of phosphate capping on the high temperature thermal stability and magnetic properties of magnetite (Fe3O4) nanoparticles synthesized through a single-step co-precipitation method. The prepared magnetic nanoparticles are characterized using various techniques. When annealed in air, the phosphate capped nanoparticle undergoes a magnetic to non-magnetic phase transition at a temperature of 689 °C as compared to 580 °C in the uncoated nanoparticle of similar size. The observed high temperature phase stability of phosphate capped nanoparticle is attributed to the formation of a phosphocarbonaceous shell over the nanoparticles, which acts as a covalently attached protective layer and improves the thermal stability of the core material by increasing the activation energy. The phosphocarbonaceous shell prevents the intrusion of heat, oxygen, volatiles, and mass into the magnetic core. At higher temperatures, the coalescence of nanoparticles occurs along with the restructuring of the phosphocarbonaceous shell into a vitreous semisolid layer on the nanoparticles, which is confirmed from the small angle X-ray scattering, Fourier transform infra red spectroscopy, and transmission electron microscopy measurements. The probable mechanism for the enhancement of thermal stability of phosphocarbonaceous capped nanoparticles is discussed.

Muthukumaran, T.; Philip, John

2014-06-01

125

Synergistic effect of silver seeds and organic modifiers on the morphology evolution mechanism of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Triangular, truncated triangular, quadrangular, hexagonal, and net-structured silver nanoplates as well as decahedral silver nanoparticles were manipulatively prepared starting from silver nitrate and silver seeds in the presence of poly(ethylene glycol) (PEG), poly( N-vinyl pyrrolidone) (PVP), and Tween 80 at room temperature, respectively. UV-vis spectroscopy, XRD, HRTEM, SAED, and FTIR were used to illustrate the crystal growth process and to characterize the resultant silver nanoparticles. It was found that the silver seeds and organic modifiers synergistically affected the morphology evolution of the silver nanoparticles. The co-presence of silver seeds and PEG was beneficial to the formation of triangular and truncated triangular silver nanoplates; the silver seeds and PVP favored the formation of polygonal silver nanoplates; the silver seeds and Tween 80 preferred to the formation of net-structured silver plates. The morphology evolution of the resultant silver nanoparticles was correlated with the crystallinity of the silver seeds and the adsorption ability of the organic modifiers on the crystal surfaces.

Wang, Aili; Yin, Hengbo; Ren, Min; Liu, Yuming; Jiang, Tingshun

2008-08-01

126

Oxidation of Ag nanoparticles in aqueous media: Effect of particle size and capping  

NASA Astrophysics Data System (ADS)

Many applications and environmental impact of silver-bearing nanomaterials critically depend upon their specific reactivity, which is still poorly understood. Here, silver nanoparticles (Ag NPs) of about 3-5 nm and 10-12 nm in diameter, uncapped and capped with L-glucose or citrate, were prepared, characterized using UV-vis absorption spectroscopy, SAXS, TEM, and their (electro)chemical oxidation was examined in comparison with each other and bulk metal applying scanning tunneling microscopy and spectroscopy, cyclic voltammetry, and XPS. A resistive switching effect was found in the tunneling spectra measured in air at the smaller uncapped Ag NPs deposited on HOPG and was interpreted in terms of Ag transfer between the particle and the probe. The anodic oxidation of these Ag NPs in 1 M NaOH yielded 3D Ag2O, while only a layer of "primary" Ag(I) oxide emerged on larger uncapped nanoparticles during the potential sweep. The formation of AgO at higher potentials proceeded readily at the "primary" oxide but was retarded at the smaller NPs. The citrate- and glucose-capping substantially impeded the formation both of Ag2O and AgO. The findings highlighted, particularly, a non-trivial effect of particle size and transient mobilization of Ag species on the reactions of silver nanoparticles.

Mikhlin, Yuri L.; Vishnyakova, Elena A.; Romanchenko, Alexander S.; Saikova, Svetlana V.; Likhatski, Maxim N.; Larichev, Yurii V.; Tuzikov, Fedor V.; Zaikovskii, Vladimir I.; Zharkov, Sergey M.

2014-04-01

127

Environmental and Human Health Issues of Silver Nanoparticles Applications  

Microsoft Academic Search

\\u000a The significant growth in applications of silver nanoparticles across ­various branches of industry as well as in consumer\\u000a products has caused concerns that nanosilver may have a toxic effect on the environment and human health and may have implications\\u000a for eco-terorism. This paper presents research on antimicrobial effects of silver nanoparticles. We studied the cytotoxicity\\u000a of silver nanoparticles via an

Renat R. Khaydarov; Rashid A. Khaydarov; Svetlana Evgrafova; Stefanie Wagner; Seung Y. Cho

128

Subchronic inhalation toxicity of silver nanoparticles.  

PubMed

The subchronic inhalation toxicity of silver nanoparticles was studied in Sprague-Dawley rats. Eight-week-old rats, weighing approximately 253.2 g (males) and 162.6 g (females), were divided into four groups (10 rats in each group): fresh-air control, low dose (0.6 x 10(6) particle/cm(3), 49 microg/m(3)), middle dose (1.4 x 10(6) particle/cm(3), 133 microg/m(3)), and high dose (3.0 x 10(6) particle/cm(3), 515 microg/m(3)). The animals were exposed to silver nanoparticles (average diameter 18-19 nm) for 6 h/day, 5 days/week, for 13 weeks in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and pulmonary function tests were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry tests, and the organ weights were measured. Bile-duct hyperplasia in the liver increased dose dependently in both the male and female rats. Histopathological examinations indicated dose-dependent increases in lesions related to silver nanoparticle exposure, including mixed inflammatory cell infiltrate, chronic alveolar inflammation, and small granulomatous lesions. Target organs for silver nanoparticles were considered to be the lungs and liver in the male and female rats. No observable adverse effect level of 100 microg/m(3) is suggested from the experiments. PMID:19033393

Sung, Jae Hyuck; Ji, Jun Ho; Park, Jung Duck; Yoon, Jin Uk; Kim, Dae Sung; Jeon, Ki Soo; Song, Moon Yong; Jeong, Jayoung; Han, Beom Seok; Han, Jeong Hee; Chung, Yong Hyun; Chang, Hee Kyung; Lee, Ji Hyun; Cho, Myung Haing; Kelman, Bruce J; Yu, Il Je

2009-04-01

129

Mechanism of Silver Nanoparticles as a Disinfectant  

Microsoft Academic Search

Using environmentally friendly synthesis techniques, monodispersive silver nanoparticles (AgNPs) were engineered. These particles exhibited bactericidal activity against Escherichia coli under both light and dark conditions. Unlike sodium hypochlorite, which demonstrated almost immediate disinfection, AgNPs required 30 min. In contrast to hypochlorite, however, the minimum dose of AgNPs decreased as the incubation time increased to less than 1 part per million.

Sajid Bashir; Karthik Chamakura; Rafael Perez-Ballestero; Zhiping Luo; Jingbo Liu

2011-01-01

130

Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent  

NASA Astrophysics Data System (ADS)

Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV-vis spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms and photoacoustic spectroscopy (PAS).

Zienkiewicz-Strza?ka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

2013-02-01

131

Silver nanoparticle studded porous polyethylene scaffolds: bacteria struggle to grow on them while mammalian cells thrive  

NASA Astrophysics Data System (ADS)

Silver nanoparticle studded scaffolds were prepared by exploiting the Ag+ ion reducing activity of sophorolipids--a class of `glycolipids' that cap the ensuing nanoparticles as well. To achieve this, the porous polyethylene scaffolds are subjected to N2 + H2 plasma treatment, in the first step. Subsequently the sophorolipids are covalently attached to the amine groups on the polymer surface through simple amide chemistry to yield sophorolipid grafted polymer scaffolds. These are then exposed to Ag+ ions under appropriate conditions leading to the formation of silver nanoparticles immobilized on the polymer scaffolds. It has been found that while bacteria do not survive on these silver studded scaffolds, CHO-K1 cells thrive on them making them good candidates for tissue engineering and bio-implant applications.Silver nanoparticle studded scaffolds were prepared by exploiting the Ag+ ion reducing activity of sophorolipids--a class of `glycolipids' that cap the ensuing nanoparticles as well. To achieve this, the porous polyethylene scaffolds are subjected to N2 + H2 plasma treatment, in the first step. Subsequently the sophorolipids are covalently attached to the amine groups on the polymer surface through simple amide chemistry to yield sophorolipid grafted polymer scaffolds. These are then exposed to Ag+ ions under appropriate conditions leading to the formation of silver nanoparticles immobilized on the polymer scaffolds. It has been found that while bacteria do not survive on these silver studded scaffolds, CHO-K1 cells thrive on them making them good candidates for tissue engineering and bio-implant applications. Electronic supplementary information (ESI) available: See DOI: 10.1039/c1nr10152d

D'Britto, Virginia; Kapse, Harsha; Babrekar, Harshada; Prabhune, A. A.; Bhoraskar, S. V.; Premnath, V.; Prasad, B. L. V.

2011-07-01

132

Synthesis and characterization of silver nanoparticles in AOT microemulsion system  

NASA Astrophysics Data System (ADS)

Colloidal silver nanoparticles have been synthesized in water-in-oil microemulsion using silver nitrate solubilized in the water core of one microemulsion as source of silver ions, hydrazine hydrate solubilized in the water core of another microemulsion as reducing agent, dodecane as the oil phase, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as the surfactant. The UV-vis absorption spectra and transmission electron microscopy (TEM) have been used to trace the growth process and elucidate the structure of the silver nanoparticles. UV-vis spectra show that the Ag4+ intermediates formed at early stages of the reaction and then the clusters grow or aggregate to larger nanoparticles. TEM micrographs confirm that the silver nanoparticles are all spherical. The resulting particles have a very narrow size distribution. Meanwhile, the diameter size of the particles is so small that the smallest mean diameter is only 1.6 nm. IR results show that the surfactant molecules are strongly adsorbed on the surface of silver particles through a coordination bond between the silver atom and the sulfonic group of AOT molecules, which endows the particles with a good stability in oil solvents. As dodecane is used as oil solvent to prepare silver nanoparticles, the formed nano-silver sol is almost nontoxic. As a result, the silver nanoparticles need not be separated from the reaction solution and the silver sol may be directly used in antibacterial fields.

Zhang, Wanzhong; Qiao, Xueliang; Chen, Jianguo

2006-11-01

133

Biologically inspired stealth peptide-capped gold nanoparticles.  

PubMed

Introduction into the human body makes most nanoparticle systems susceptible to aggregation via nonspecific protein binding. Here, we developed a peptide-capped gold nanoparticle platform that withstands aggregation in undiluted human serum at 37 °C for 24 h. This biocompatible and natural system is based on mimicking human proteins which are enriched in negatively charged glutamic acid and positively charged lysine residues on their surface. The multifunctional EKEKEKE-PPPPC-Am peptide sequence consists of a stealth glutamic acid/lysine portion combined with a surface anchoring linker containing four prolines and a cysteine. Particle stability was measured via optical spectroscopy and dynamic light scattering in single protein, high salt, and undiluted human serum solutions. In vitro cell experiments demonstrate EKEKEKE-PPPPC-Am capped gold nanoparticles effectively minimize nonspecific cell uptake by nonphagocytic bovine aortic endothelial cells and phagocytic murine macrophage RAW 264.7 cells. Cytotoxicity studies show that peptide-capped gold nanoparticles do not affect cell viability. Finally, the peptide EKEKEKE-PPPPC-Am was extended with cyclic RGD to demonstrate specific cell targeting and stealth without using poly(ethylene glycol). Adding the functional peptide via peptide sequence extension avoids complex conjugation chemistries that are used for connection to synthetic materials. Inductively coupled plasma mass spectroscopy results indicate high aortic bovine endothelial cell uptake of c[RGDfE(SGG-KEKEKE-PPPPC-Am)] capped gold nanoparticles and low uptake of the control scrambled sequence c[RDGfE(SGG-KEKEKE-PPPPC-Am)] capped gold nanoparticles. PMID:24483727

Nowinski, Ann K; White, Andrew D; Keefe, Andrew J; Jiang, Shaoyi

2014-02-25

134

Formation and optical properties of silver perfluorodecanethiolate nanoparticles.  

PubMed

This article reports a new catalytic method for preparing nanoparticles of silver thiolate from silver nanoparticles scattered on a ZrO2-coated substrate. Such nanoparticles transform into silver (perfluoro) decanethiolate after immersion in a solution of (perfluoro) decanethiol in heptane. These transformations occur at room temperature and are catalysed by ZrO2. The silver decanethiolate is obtained as lamellar crystals while the silver perfluorodecanethiolate is obtained in amorphous state. The modifications of the sample optical properties due to this latter compound are studied in correlation with its surface morphology, according to different preparation conditions. It is shown that an antireflective effect in addition to the damping of the plasmon band of the silver nanoparticles can be responsible for a large transmittance enhancement in the near-UV and visible ranges. These effects are modulated by the possible oxidation of the silver nanoparticle surface. In the absence of silver oxidation, the silver perfluorodecanethiolate is obtained as contiguous spheroidal nanoparticles, while, in the presence of silver oxidation, this compound is mainly obtained as entangled nanowires. PMID:23953653

Brenier, Roger; Piednoir, Agnès; Bessueille, François; Penuelas, José; Terrier, Nicolas

2013-10-15

135

Removal of silver nanoparticles by coagulation processes.  

PubMed

Commercial use of silver nanoparticles (AgNPs) will lead to a potential route for human exposure via potable water. Coagulation followed by sedimentation, as a conventional technique in the drinking water treatment facilities, may become an important barrier to prevent human from AgNP exposures. This study investigated the removal of AgNP suspensions by four regular coagulants. In the aluminum sulfate and ferric chloride coagulation systems, the water parameters slightly affected the AgNP removal. However, in the poly aluminum chloride and polyferric sulfate coagulation systems, the optimal removal efficiencies were achieved at pH 7.5, while higher or lower of pH could reduce the AgNP removal. Besides, the increasing natural organic matter (NOM) would reduce the AgNP removal, while Ca(2+) and suspended solids concentrations would also affect the AgNP removal. In addition, results from the transmission electron microscopy and X-ray diffraction showed AgNPs or silver-containing nanoparticles were adsorbed onto the flocs. Finally, natural water samples were used to validate AgNP removal by coagulation. This study suggests that in the case of release of AgNPs into the source water, the traditional water treatment process, coagulation/sedimentation, can remove AgNPs and minimize the silver ion concentration under the well-optimized conditions. PMID:23973474

Sun, Qian; Li, Yan; Tang, Ting; Yuan, Zhihua; Yu, Chang-Ping

2013-10-15

136

Fluorescence of pyrene in inhomogeneous media containing silver nanoparticles  

NASA Astrophysics Data System (ADS)

Pyrene fluorescence in inhomogeneous media based on ionic detergents containing silver nanoparticles with different morphologies is investigated. An increase in pyrene monomer emissions in the spectral range of 400-500 nm is observed, due to the resonance between electronic transitions in pyrene molecules in that region and the plasmonic oscillations of silver nanoparticles.

Romanovskaya, G. I.

2014-05-01

137

Biogenic silver nanoparticles with chlorogenic acid as a bioreducing agent.  

PubMed

We report the synthesis of biogenic silver nanoparticles using chlorogenic acid as a bioreducing agent. Chlorogenic acid is a polyphenol compound abundant in coffee. UV-Vis spectra showed the characteristic surface plasmon resonance band at 415 nm, indicating the successful synthesis of biogenic silver nanoparticles. Spherical and irregular shaped nanoparticles were observed with an average diameter of 19.29 +/- 8.23 nm. The reaction yield from silver ion to silver nanoparticles was observed as 95.43% by using inductively coupled plasma-mass spectrometry. Fourier transform infrared spectra revealed that the -C = O groups of chlorogenic acid may coordinate or complex into silver nanoparticles. Biogenic silver nanoparticles exerted higher antibacterial activity against Gram-negative bacteria than against Gram-positive bacteria. Interestingly, a comparable antibacterial activity to a standard antibiotic was observed against two strains of Pseudomonas aeruginosa (minimum inhibitory concentration of 0.66 microg/mL). The synergistic effect of a combination of silver nanoparticles and chlorogenic acid on antibacterial activity is obvious, leading to approximately 8-fold enhancement in the case of Pseudomonas aeruginosa when compared with chlorogenic acid alone. The present report suggests that a pure compound with a plant origin is capable of being a bioreducing agent for the synthesis of biogenic silver nanoparticles with superior antibacterial activity, opening up many applications in nanomedicine and nanobiotechnology. PMID:23882836

Noh, Hwa Jung; Kim, Hyun-Seok; Jun, Sang Hui; Kang, Young-Hwa; Cho, Seonho; Park, Youmie

2013-08-01

138

Chitin membranes containing silver nanoparticles for wound dressing application.  

PubMed

Silver nanoparticles are gaining importance as an antimicrobial agent in wound dressings. Chitin is a biopolymer envisioned to promote rapid dermal regeneration and accelerate wound healing. This study was focused on the evaluation of chitin membranes containing silver nanoparticles for use as an antimicrobial wound dressing. Silver nanoparticles were synthesised by gamma irradiation at doses of 50 kGy in the presence of sodium alginate as stabiliser. The UV-Vis absorption spectra of nanoparticles exhibited an absorption band at 415-420 nm, which is the typical plasmon resonance band of silver nanoparticles. The peaks in the X-ray diffraction (XRD) pattern are in agreement with the standard values of the face-centred cubic silver. Transmission electron microscopy (TEM) images indicate silver nanoparticles with spherical morphology and small particle size in the range of 3-13 nm. In vitro antimicrobial tests were performed using Pseudomonas aeruginosa and Staphylococcus aureus to determine the antimicrobial efficiency of the chitin membranes containing 30, 50, 70 and 100 ppm nanosilver. No viable counts for P. aeruginosa were detected with 70 ppm silver nanoparticles dressing after 1-hour exposure. A 2-log reduction in viable cell count was observed for S. aureus after 1 hour and a 4-log reduction after 6 hours with 100 ppm nanosilver chitin membranes. This study demonstrates the antimicrobial capability of chitin membranes containing silver nanoparticles. The chitin membranes with 100 ppm nanosilver showed promising antimicrobial activity against common wound pathogens. PMID:22958740

Singh, Rita; Singh, Durgeshwer

2014-06-01

139

Tuning of optical properties of PMMA by incorporating silver nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocomposite films of Poly (methylmethacrylate) filled with different concentration of silver nanoparticles were prepared by ex-situ method. Firstly, silver nanoparticles were obtained by reducing the aqueous solution of silver nitrate with sodium borohydride then Ag/PMMA films were prepared by mixing colloidal solution of silver nanoparticles with solution of polymer. From absorption and specular reflection spectra, the optical band gap and refractive index (n) have been calculated. The decrease in optical bandgap and increase in refractive index has been indicative of the modifications in optical band structure of the PMMA matrix.

Alisha; Rozra, Jyoti; Saini, Isha; Sharma, Annu; Sharma, Pawan

2012-06-01

140

A facile route to synthesize nanogels doped with silver nanoparticles  

PubMed Central

In this work, we describe a simple method to prepare hybrid nanogels consisting of a biocompatible core-shell polymer host containing silver nanoparticles. First, the nanogels (NG, ~160 nm) containing a lysozyme rich core and a dextran rich shell, are prepared via Maillard and heat-gelation reactions. Second, silver nanoparticles (Ag NPs, ~5nm) are synthesized in situ in the NG solution without requiring additional reducing agents. This approach leads to stable Ag NPs located in the NG. Furthermore, we demonstrate that the amount of Ag NPs in the NG can be tuned by varying silver precursor concentration. Hybrid nanogels with silver nanoparticles have potential in antimicrobial, optical and therapeutic applications.

Ferrer, M. Carme Coll; Ferrier, Robert C.; Eckmann, David M.; Composto, Russell J.

2012-01-01

141

Synthesis of silver nanoparticles in melts of amphiphilic polyesters  

NASA Astrophysics Data System (ADS)

The current work presents a one-step procedure for the synthesis of amphiphilic silver nanoparticles suitable for production of silver-filled polymeric materials. This solvent free synthesis via reduction of Tollens’ reagent as silver precursor in melts of amphiphilic polyesters consisting of hydrophilic poly(ethylene glycol) blocks and hydrophobic alkyl chains allows the production of silver nanoparticles without any by-product formation. This makes them especially interesting for the production of medical devices with antimicrobial properties. In this article the influences of the chain length of the hydrophobic block in the amphiphilic polyesters and the process temperature on the particle size distribution (PSD) and the stability of the particles against agglomeration are discussed. According to the results of spectroscopic and viscosimetric investigations the silver precursor is reduced to elemental silver nanoparticles by a single electron transfer process from the poly(ethylene glycol) chain to the silver ion.

Vasylyev, S.; Damm, C.; Segets, D.; Hanisch, M.; Taccardi, N.; Wasserscheid, P.; Peukert, W.

2013-03-01

142

Silver and gold nanoparticles for sensor and antibacterial applications  

NASA Astrophysics Data System (ADS)

Green biogenic method for the synthesis of gold and silver nanoparticles using Solanum lycopersicums extract as reducing agent was studied. The biomolecules present in the extract was responsible for reduction of Au3+ and Ag+ ions from HAuCl4 and AgNO3 respectively. The prepared nanoparticles were characterized by UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) technique to identify the size, shape of nanoparticles and biomolecules act as reducing agents. UV-visible spectra show the surface plasmon resonance peak at 546 nm and 445 nm corresponding to gold and silver nanoparticles respectively. Crystalline nature of the nanoparticles was evident from TEM images and XRD analysis. TEM images showed average size of 14 nm and 12 nm for prepared gold and silver nanoparticles respectively. FTIR analysis provides the presence of biomolecules responsible for the reduction and stability of the prepared silver and gold nanoparticles. XRD analysis of the silver and gold nanoparticles confirmed the formation of metallic silver and gold. The prepared gold and silver nanoparticles show good sensing and antimicrobial activity.

Bindhu, M. R.; Umadevi, M.

2014-07-01

143

Silver and gold nanoparticles for sensor and antibacterial applications.  

PubMed

Green biogenic method for the synthesis of gold and silver nanoparticles using Solanum lycopersicums extract as reducing agent was studied. The biomolecules present in the extract was responsible for reduction of Au(3+) and Ag(+) ions from HAuCl4 and AgNO3 respectively. The prepared nanoparticles were characterized by UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) technique to identify the size, shape of nanoparticles and biomolecules act as reducing agents. UV-visible spectra show the surface plasmon resonance peak at 546 nm and 445 nm corresponding to gold and silver nanoparticles respectively. Crystalline nature of the nanoparticles was evident from TEM images and XRD analysis. TEM images showed average size of 14 nm and 12 nm for prepared gold and silver nanoparticles respectively. FTIR analysis provides the presence of biomolecules responsible for the reduction and stability of the prepared silver and gold nanoparticles. XRD analysis of the silver and gold nanoparticles confirmed the formation of metallic silver and gold. The prepared gold and silver nanoparticles show good sensing and antimicrobial activity. PMID:24657466

Bindhu, M R; Umadevi, M

2014-07-15

144

Sonochemical synthesis of silver nanoparticles using starch: a comparison.  

PubMed

A novel approach was applied to synthesize silver nanoparticles using starch under sonication. Colloidal silver nanoparticles solution exhibited an increase of absorption from 420 to 440?nm with increase starch quantity. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, amorphous, silver nanoparticles of diameter ranging from 23 to 97?nm with mean particle size of 45.6?nm. Selected area electron diffraction (SAED) confirmed partial crystalline and amorphous nature of silver nanoparticles. Silver nanoparticles synthesized in this manner can be used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications. The optimized reaction conditions include 10?ml of 1?mM AgNO3, 25?mg starch, 11 pH range, and sonication for 20?min at room temperature. PMID:24587771

Kumar, Brajesh; Smita, Kumari; Cumbal, Luis; Debut, Alexis; Pathak, Ravinandan Nath

2014-01-01

145

Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity  

NASA Astrophysics Data System (ADS)

Polyhexamethylene biguanide (PHMB), a broad spectrum disinfectant against many pathogens, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles. The particles formed were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering, electrophoretic mobility, and TEM to measure their morphology and surface chemistry. PHMB-functionalized silver nanoparticles were then evaluated for their antimicrobial activity against a gram-negative bacterial strain, Escherichia coli. These silver nanoparticles were found to have about 100 times higher bacteriostatic and bactericidal activities, compared to the previous reports, due to the combined antibacterial effect of silver nanoparticles and PHMB. In addition to other applications, PHMB-functionalized silver nanoparticles would be extremely useful in textile industry due to the strong interaction of PHMB with cellulose fabrics.

Ashraf, Sumaira; Akhtar, Nasrin; Ghauri, Muhammad Afzal; Rajoka, Muhammad Ibrahim; Khalid, Zafar M.; Hussain, Irshad

2012-05-01

146

Colored and functional silver nanoparticle-wool fiber composites.  

PubMed

Silver nanoparticles utilizing the surface plasmon resonance effect of silver have been used to color merino wool fibers as well as imparting antimicrobial and antistatic properties to them to produce a novel silver nanoparticle-wool composite material. This is accomplished by the reduction of silver ions in solution by trisodium citrate (TSC) in the presence of merino wool fibers or fabrics. The silver metal nanoparticles simultaneously bind to the amino acids of the keratin protein in the wool fibers using TSC as the linker. The colors of the resulting merino wool-silver nanoparticle composites range from yellow/brown to red/brown and then to brown/black, because of the surface plasmon resonance effect of silver, and are tuned by controlling the reduction of silver ions to silver nanoparticles to give the required particle size on the fiber surface. In addition to the surface plasmon resonance optical effects, the silver nanoparticle-wool composites exhibit effective antimicrobial activity, thus inhibiting the growth of microbes and also an increase in the electrical conductivity, imparting antistatic properties to the fibers. Therefore, silver nanoparticles function as a simultaneous colorant and antimicrobial and antistatic agent for wool. Chemical and physical characterizations of the silver nanoparticle-merino wool composite materials have been carried out using scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, synchrotron radiation X-ray diffraction, atomic absorption spectroscopy, X-ray photoelectron spectroscopy, direct-current electrical conductivity measurements, wash-fast and rub-fast tests, and antimicrobial tests. PMID:21381777

Kelly, Fern M; Johnston, James H

2011-04-01

147

Comparison of bioconcentration of ionic silver and silver nanoparticles in zebrafish eleutheroembryos.  

PubMed

The production of silver nanoparticles has reached nowadays high levels. Bioconcentration studies, information on persistence and toxicity are fundamental to assess their global risk and thus necessary to establish legislations regarding their use. Previous studies on silver nanoparticle toxicity have determined a clear correlation between their chemical stability and toxicity. In this work, experimental conditions able to assure silver nanoparticles stability have been optimized. Then, zebrafish (Danio rerio) eleutheroembryos were exposed to ionic silver and to Ag NPs for comparison purposes. A protocol alternative to the OECD 305 technical guideline was used. To determine silver concentration in both the eleutheroembryos and the exposure media, an analytical method consisting in ultrasound assisted extraction, followed by inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry, was developed. Then, bioconcentration factors were calculated. The results revealed that ionic silver was more accumulative for zebrafish eleutheroembryos than nanoparticles at the levels tested. PMID:24858804

López-Serrano, A; Muñoz-Olivas, R; Sanz-Landaluze, J; Olasagasti, M; Rainieri, S; Cámara, C

2014-08-01

148

Impact of Environmental Conditions (pH, Ionic Strength, And Electrolyte Type) On The Surface Charge And Aggregation Of Silver Nanoparticles Suspensions  

EPA Science Inventory

The impact of capping agents and environmental conditions (pH, ionic strength, and background electrolytes) on surface charge and aggregation potential of silver nanoparticles (AgNPs) suspensions were investigated. Capping agents are chemicals used in the synthesis of nanopartic...

149

Synthesis and applications of novel silver nanoparticle structures  

NASA Astrophysics Data System (ADS)

The field of nanotechnology is rapidly expanding across disciplines as each new development is realized. New exciting technologies are being driven by advances in the application of nanotechnology; including biochemical, optical, and semiconductors research. This thesis will focus on the use of silver nanoparticles as optical labels on cells, methods of forming different small structures of silver nanoparticles, as well as the use of silver nanoparticles in the development of a photovoltaic cell. Silver nanoparticles have been modified with self-assembled monolayers of hydroxyl-terminated long chain thiols and encapsulated with a silica shell. The resulting core-shell nanoparticles were used as optical labels for cell analysis using flow cytometry and microscopy. The excitation of plasmon resonances in nanoparticles results in strong depolarized scattering of visible light permitting detection at the single nanoparticle level. The nanoparticles were modified with neutravidin via epoxide-azide coupling chemistry and biotinylated antibodies targeting cell surface receptors were bound to the nanoparticle surface. The nanoparticle labels exhibited long-term stability under physiological conditions without aggregation or silver ion leaching. Labeled cells exhibited two orders of magnitude enhancement of the scattering intensity compared to unlabeled cells. Dimers of silver nanoparticles have been fabricated by first immobilizing a monolayer of single silver nanoparticles onto poly(4-vinylpyridine) covered glass slides. The monolayer was then exposed to adenine, which has two amines which will bind to silver. The nanoparticle monolayer, now modified with adenine, is exposed to a second suspension of nanoparticles which will bind with the amine modified monolayer. Finally, a thin silica shell is formed about the structure via solgel chemistry to prevent dissolution or aggregation upon sonication/striping. Circular arrays of silver nanoparticels are developed using a template base self assembly. A 1.5 micron silica sphere is bound to poly(4-vinylpyridine) coated glass and used as a template. a mask of silica monoxide is vacuum deposited atop the spheres/glass leaving a ring just below the sphere untouched and able to bind silver nanoparticles. Optical microscopy reveal interesting results under depolarized light conditions, but ultimate structural analysis has proven elusive. Semiconducting p-type cuprous oxide was electrochemically deposited on both silver and indium tin oxide electrodes. Silver nanoparticles were incorporated into the architecture either atop the cuprous oxide or sandwiched between cuprous oxide and n-type material. Increases in photocurrent were observed in both cases and further work must be conducted to optimize a solid state device for photovoltaic applications.

Dukes, Kyle

150

Successively amplified electrochemical immunoassay based on biocatalytic deposition of silver nanoparticles and silver enhancement  

Microsoft Academic Search

A successively signal-amplified electrochemical immunoassay has been reported on the basis of the biocatalytic deposition of silver nanoparticles with their subsequent enlargement by nanoparticle-promoted catalytic precipitation of silver from the silver-enhancer solution. The immunoassay was carried out based on a heterogeneous sandwich procedure using polystyrene microwells to immobilize antibody. After all the processes comprising the formation of immunocomplex, biocatalytic deposition

Zhao-Peng Chen; Zhao-Feng Peng; Yan Luo; Bo Qu; Jian-Hui Jiang; Xiao-Bing Zhang; Guo-Li Shen; Ru-Qin Yu

2007-01-01

151

Structural characterisation of alkyl amine-capped zinc sulphide nanoparticles  

PubMed Central

Nanoparticles capped with amine ligands with different steric properties, dodecylamine and oleylamine, respectively, are investigated in the solid state as well as in solution. A combined X-ray diffraction, small angle X-ray scattering and electron microscopy investigation showed that the nanoparticles exhibit the sphalerite modification of ZnS as crystal phase with a diameter of 3–5 nm. A close packing of the monocrystalline nanoparticles in the solid state is observed. However, in the dodecylamine sample, besides spherical particles, a fraction of the nanoparticles is elongated. The nanoparticles are readily resoluble in apolar solvents like hexane. Dynamic light scattering (DLS) and SAXS investigations of the solutions reveal that the nanoparticles are dissolved as singular particles. In the case of oleylamine-capped ZnS, a defined core–shell structure with a ZnS core with a diameter of 4 nm and an organic shell with a thickness of approximately 2 nm have been found. Dodecylamine-capped nanoparticles slightly tend to form agglomerates with a diameter of approximately 40 nm.

Kremser, Gabriele; Rath, Thomas; Kunert, Birgit; Edler, Michael; Fritz-Popovski, Gerhard; Resel, Roland; Letofsky-Papst, Ilse; Grogger, Werner; Trimmel, Gregor

2012-01-01

152

Circular dichroism study of chiral biomolecules conjugated with silver nanoparticles  

NASA Astrophysics Data System (ADS)

Chiral biomolecules conjugated with silver nanoparticles were investigated by circular dichroism (CD) spectroscopy. Silver nanoparticles were prepared by the citrate reduction method and were characterized by UV spectroscopy and TEM. Conjugation of thiol group-containing biomolecules, such as cysteine, glutathione and penicillamine, with silver nanoparticles resulted in the generation of new characteristic CD signals in the region of 240-400 nm, whereas no CD signal changes were found with lysine or glutamine. Association through hydrogen bonding among the biomolecules is considered to be essential for CD signal generation, which was confirmed by experiment with cysteine methyl ester. Interestingly, Au nanoparticles were not found to generate CD signals in the wavelength region tested, indicating that this phenomenon is a unique feature of silver nanoparticles, distinguished from gold nanoparticles.

Li, Taihua; Park, Hyun Gyu; Lee, Hee-Seung; Choi, Seong-Ho

2004-10-01

153

Toxicity of silver nanoparticles at the air-liquid interface.  

PubMed

Silver nanoparticles are one of the most prevalent nanomaterials in consumer products. Some of these products are likely to be aerosolized, making silver nanoparticles a high priority for inhalation toxicity assessment. To study the inhalation toxicity of silver nanoparticles, we have exposed cultured lung cells to them at the air-liquid interface. Cells were exposed to suspensions of silver or nickel oxide (positive control) nanoparticles at concentrations of 2.6, 6.6, and 13.2 ? g cm(-2) (volume concentrations of 10, 25, and 50 ? g ml(-1)) and to 0.7 ? g cm(-2) silver or 2.1 ? g cm(-2) nickel oxide aerosol at the air-liquid interface. Unlike a number of in vitro studies employing suspensions of silver nanoparticles, which have shown strong toxic effects, both suspensions and aerosolized nanoparticles caused negligible cytotoxicity and only a mild inflammatory response, in agreement with animal exposures. Additionally, we have developed a novel method using a differential mobility analyzer to select aerosolized nanoparticles of a single diameter to assess the size-dependent toxicity of silver nanoparticles. PMID:23484109

Holder, Amara L; Marr, Linsey C

2013-01-01

154

Toxicity of Silver Nanoparticles at the Air-Liquid Interface  

PubMed Central

Silver nanoparticles are one of the most prevalent nanomaterials in consumer products. Some of these products are likely to be aerosolized, making silver nanoparticles a high priority for inhalation toxicity assessment. To study the inhalation toxicity of silver nanoparticles, we have exposed cultured lung cells to them at the air-liquid interface. Cells were exposed to suspensions of silver or nickel oxide (positive control) nanoparticles at concentrations of 2.6, 6.6, and 13.2??g cm?2 (volume concentrations of 10, 25, and 50??g?ml?1) and to 0.7??g?cm?2 silver or 2.1??g?cm?2 nickel oxide aerosol at the air-liquid interface. Unlike a number of in vitro studies employing suspensions of silver nanoparticles, which have shown strong toxic effects, both suspensions and aerosolized nanoparticles caused negligible cytotoxicity and only a mild inflammatory response, in agreement with animal exposures. Additionally, we have developed a novel method using a differential mobility analyzer to select aerosolized nanoparticles of a single diameter to assess the size-dependent toxicity of silver nanoparticles.

Holder, Amara L.; Marr, Linsey C.

2013-01-01

155

Optimization of Biological Synthesis of Silver Nanoparticles using Fusarium oxysporum  

PubMed Central

Silver nanoparticles are increasingly used in various fields of biotechnology and applications in the medicine. Objectives of this study were optimization of production of silver nanoparticles using biotransformations by Fusarium oxysporum, and a further study on the location of nanoparticles synthesis in this microorganism. The reaction mixture contained the following ingredients (final concentrations): AgNO3 (1-10 mM) as the biotransformation substrate, biomass as the biocatalyst, glucose (560 mM) as the electron donor, and phosphate buffer (pH= 7, 100 mM). The samples were taken from the reaction mixtures at different times, and the absorbance (430 nm) of the colloidal suspensions of silver nanoparticles hydrosols was read freshly (without freezing) and immediately after dilution (1:40). SEM and TEM analyses were performed on selected samples. The presence of AgNO3 (0.1 mM) in the culture as enzyme inducer, and glucose (560 mM) as electron donor had positive effects on nanoparticle production. In SEM micrographs, silver nanoparticles were almost spherical, single (25-50 nm) or in aggregates (100 nm), attached to the surface of biomass. The reaction mixture was successfully optimized to increase the yield of silver nanoparticles production. More details of the location of nanoparticles production by this fungus were revealed, which support the hypothesis that silver nanoparticles are synthesized intracellularly and not extracellularly.

Korbekandi, Hassan; Ashari, Zeynab; Iravani, Siavash; Abbasi, Sajjad

2013-01-01

156

Optimization of Biological Synthesis of Silver Nanoparticles using Fusarium oxysporum.  

PubMed

Silver nanoparticles are increasingly used in various fields of biotechnology and applications in the medicine. Objectives of this study were optimization of production of silver nanoparticles using biotransformations by Fusarium oxysporum, and a further study on the location of nanoparticles synthesis in this microorganism. The reaction mixture contained the following ingredients (final concentrations): AgNO3 (1-10 mM) as the biotransformation substrate, biomass as the biocatalyst, glucose (560 mM) as the electron donor, and phosphate buffer (pH= 7, 100 mM). The samples were taken from the reaction mixtures at different times, and the absorbance (430 nm) of the colloidal suspensions of silver nanoparticles hydrosols was read freshly (without freezing) and immediately after dilution (1:40). SEM and TEM analyses were performed on selected samples. The presence of AgNO3 (0.1 mM) in the culture as enzyme inducer, and glucose (560 mM) as electron donor had positive effects on nanoparticle production. In SEM micrographs, silver nanoparticles were almost spherical, single (25-50 nm) or in aggregates (100 nm), attached to the surface of biomass. The reaction mixture was successfully optimized to increase the yield of silver nanoparticles production. More details of the location of nanoparticles production by this fungus were revealed, which support the hypothesis that silver nanoparticles are synthesized intracellularly and not extracellularly. PMID:24250635

Korbekandi, Hassan; Ashari, Zeynab; Iravani, Siavash; Abbasi, Sajjad

2013-01-01

157

Tunable variation of optical properties of polymer capped gold nanoparticles  

Microsoft Academic Search

Optical properties of polymer capped gold nanoparticles of various sizes (diameter 3–6 nm) have been studied. We present a\\u000a new scheme to extract size dependent variation of total dielectric function of gold nanoparticles from measured UV-Vis absorption\\u000a data. The new scheme can also be used, in principle, for other related systems as well. We show how quantum effect, surface\\u000a atomic

M. Haridas; S. Srivastava; J. K. Basu

2008-01-01

158

Fabrication of tunable grating with silver nanoparticles  

NASA Astrophysics Data System (ADS)

A tunable grating was fabricated with silver nanoparticles in a gradient increase of nanoparticle size along the grating direction in this study. Owing to the gradual increment of the nanoparticle size, the first order diffraction efficiencies of incident light presented as a function of the impinging position of the probe beam. Via a probe of monochromatic light ranged from 450 to 750 nm, the positive and the negative first order diffraction efficiency were measured by rotating the optical detector. It was noted that the maximum positive and negative diffraction efficiency appeared at around 600 and 700 nm, respectively. The difference in the peak wavelength of these two diffraction efficiency exhibited the diffraction property was strongly affected by the gradient variation of the localized surface plasmon effect. The first order diffraction efficiency spectra affected by the various excitations of the localized surface plasmons with the taper size distribution of nanoparticles were the special discovery of the study and may lead to a potential development in light modulation and manipulation.

Liu, Tung-Kai; Hung, Wen-Chi; Tsai, Ming-Shan; Tsao, Yong-Chang; Jiang, I.-Min

2009-06-01

159

Bio-conjugated silver nanoparticles: from Ocimum sanctum and role of cetyltrimethyl ammonium bromide.  

PubMed

In this paper we have reported the spectrophotometeric and transmission electron microscopic (TEM) data to the shape-directing role of cetyltrimethylammonium bromide (CTAB) on the green extra-cellular synthesis of bio-conjugated Ag-nanoparticles using Ocimum sanctum leaves extract. TEM images revealed that the nanoparticles are mostly spherical (average particle size ranged from 18 to 35nm) with some truncated triangular nanoplates, aggregated in a beautiful manner to yield locket-like silver and capped by a thin layer of biomolecules of O. sanctum, whereas nanoparticles are highly poly-dispersed in presence of CTAB. The shape and position of wavelength maxima strongly depends on the reaction time, [leaves extract] and [CTAB]. The visual observations also suggest that the prefect transparent silver sol becomes turbid in presence of CTAB after some time. PMID:23524081

Zaheer, Zoya; Rafiuddin

2013-08-01

160

Silver Nanoparticles and Graphitic Carbon Through Thermal Decomposition of a Silver/Acetylenedicarboxylic Salt  

PubMed Central

Spherically shaped silver nanoparticles embedded in a carbon matrix were synthesized by thermal decomposition of a Ag(I)/acetylenedicarboxylic acid salt. The silver nanoparticles, which are formed either by pyrolysis at 300 °C in an autoclave or thermolysis in xylene suspension at reflux temperature, are acting catalytically for the formation of graphite layers. Both reactions proceed through in situ reduction of the silver cations and polymerization of the central acetylene triple bonds and the exact temperature of the reaction can be monitored through DTA analysis. Interestingly, the thermal decomposition of this silver salt in xylene partly leads to a minor fraction of quasicrystalline silver, as established by HR-TEM analysis. The graphitic layers covering the silver nanoparticles are clearly seen in HR-TEM images and, furthermore, established by the presence of sp2carbon at the Raman spectrum of both samples.

2009-01-01

161

Ultrafast electronic relaxation processes in semiconductor nanoparticles (silver iodide, silver iodide/silver sulfide, silver bromide/silver sulfide, silver sulfide, cupric sulfide, and copper sulfide) and carotenoids  

NASA Astrophysics Data System (ADS)

This dissertation examines primarily the ultrafast dynamics of excited state charge carriers in semiconductor nanoparticles. The dissertation also briefly examines the excited state lifetimes of a few carotenoids. Understanding the dynamic properties of charge carriers in semiconductor nanoparticles is crucial for the further development of applications utilizing these systems. The dynamic properties including shallow and deep trapping as well as recombination have been studied in a variety of semiconductor nanoparticle systems. Kinetic modeling was utilized to assist in the assignment of all observed signals and the nature of the decays. The first observation of ultrafast trapping in silver halides was observed in AgI nanoparticles including the identification that interstitial silver ions may act as deep traps. Several interesting phenomena were observed in Ag2S and CuxS nanoparticles including dark shallow trap states and shallow trap state saturation leading to increased transient absorption over transient bleach with increasing excitation intensity. These observations have provided further insight into the relaxation pathways for charge carriers in semiconductor nanoparticle systems. Lifetimes of the S2 excited states of four carotenoids have also been determined. The S2 lifetime for beta-carotene was confirmed from previous fluorescence up-conversion experiments whereas the S2 lifetimes that were previously unknown for three carotenoids, violaxanthin, neaxanthin, and lutein were discovered. These experiments together demonstrate the capabilities of femtosecond pump-probe spectroscopy to characterize and better understand the processes involved in the ultrafast relaxation events in both molecular and nanoparticle systems.

Brelle, Michael Chris

162

Shape effects in plasmon resonance of individual colloidal silver nanoparticles  

Microsoft Academic Search

We present a systematic study of the effect of size and shape on the spectral response of individual silver nanoparticles. An experimental method has been developed that begins with the detection and characterization of isolated nanoparticles in the optical far field. The plasmon resonance optical spectrum of many individual nanoparticles are then correlated to their size and shape using high-resolution

J. J. Mock; M. Barbic; D. R. Smith; D. A. Schultz; S. Schultz

2002-01-01

163

Doubly localized surface plasmon resonance in bimodally distributed silver nanoparticles.  

PubMed

Growth of bimodally distributed silver nanoparticles using sequential physical vapour deposition (PVD) is reported. Growth conditions of nanoparticles are defined in the following three steps: In the first step, nanoparticles are grown at a heated substrate and then exposed to atmosphere, in the second step, nanoparticles are vacuum annealed and finally re-deposition of silver is performed in the third step. This special way of deposition leads to the formation of bimodally distributed nanoparticles. It has been investigated that by changing the deposition time, different sets of bimodally distributed nanoparticles can be grown. Localized surface plasmon resonance (LSPR) of such bimodally distributed nanoparticles generates double plasmon resonance peaks with overlapped absorption spectra. Double plasmon resonance peaks provide a quick indication of the existence of two sets of nanoparticles. LSPR spectra of such bimodally distributed nanoparticles could be modeled with double Lorentz oscillator model. Inclusion of double Lorentz oscillator model indicates that there exist two sets of non-interacting nanoparticles resonating at different plasma frequencies. It is also reported that silver nanoparticles grown at a heated substrate, again attain the new shape while being exposed to atmosphere, followed by vacuum annealing at the same temperature. This is because of physisorption of oxygen at the silver surface and change in surface free energy. The re-shaping due to the adsorbed oxygen on the surface is responsible for bimodal size distribution of nanoparticles. PMID:22905497

Ranjan, M

2012-06-01

164

Reprotoxicity of gold, silver, and gold-silver alloy nanoparticles on mammalian gametes.  

PubMed

Metal and alloy nanoparticles are increasingly developed for biomedical applications, while a firm understanding of their biocompatibility is still missing. Various properties have been reported to influence the toxic potential of nanoparticles. This study aimed to assess the impact of nanoparticle size, surface ligands and chemical composition of gold, silver or gold-silver alloy nanoparticles on mammalian gametes. An in vitro assay for porcine gametes was developed, since these are delicate primary cells, for which well-established culture systems exist and functional parameters are defined. During coincubation with oocytes for 46 h neither any of the tested gold nanoparticles nor the gold-silver alloy particles with a silver molar fraction of up to 50% showed any impact on oocyte maturation. Alloy nanoparticles with 80% silver molar fraction and pure silver nanoparticles inhibited cumulus-oocyte maturation. Confocal microscopy revealed a selective uptake of gold nanoparticles by oocytes, while silver and alloy particles mainly accumulated in the cumulus cell layer surrounding the oocyte. Interestingly sperm vitality parameters (motility, membrane integrity and morphology) were not affected by any of the tested nanoparticles. Only sporadic association of nanoparticles with the sperm plasma membrane was found by transmission electron microscopy. In conclusion, mammalian oocytes were sensitive to silver containing nanoparticles. Likely, the delicate process of completing meiosis in maternal gametes features high vulnerability towards nanomaterial derived toxicity. The results imply that released Ag(+)-ions are responsible for the observed toxicity, but the compounding into an alloy seemed to alleviate the toxic effects to a certain extent. PMID:24171189

Tiedemann, Daniela; Taylor, Ulrike; Rehbock, Christoph; Jakobi, Jurij; Klein, Sabine; Kues, Wilfried A; Barcikowski, Stephan; Rath, Detlef

2014-03-01

165

A novel bone cement impregnated with silver-tiopronin nanoparticles: its antimicrobial, cytotoxic, and mechanical properties  

PubMed Central

Post-operatory infections in orthopedic surgeries pose a significant risk. The common approach of using antibiotics, both parenterally or embedded in bone cement (when this is employed during surgery) faces the challenge of the rising population of pathogens exhibiting resistance properties against one or more of these compounds; therefore, novel approaches need to be developed. Silver nanoparticles appear to be an exciting prospect because of their antimicrobial activity and safety at the levels used in medical applications. In this paper, a novel type of silver nanoparticles capped with tiopronin is presented. Two ratios of reagents during synthesis were tested and the effect on the nanoparticles investigated through TEM, TGA, and UV-Vis spectroscopy. Once encapsulated in bone cement, only the nanoparticles with the highest amount of inorganic fraction conferred antimicrobial activity against methicillin resistant Staphylococcus aureus (MRSA) at concentrations as low as 0.1% w/w. No other characteristics of the bone cement, such as cytotoxicity or mechanical properties, were affected by the presence of the nanoparticles. Our work presents a new type of silver nanoparticles and demonstrates that they can be embedded in bone cement to prevent infections once the synthetic conditions are tailored for such applications.

Prokopovich, Polina; Leech, Ralph; Carmalt, Claire J; Parkin, Ivan P; Perni, Stefano

2013-01-01

166

Non-hazardous anticancerous and antibacterial colloidal 'green' silver nanoparticles.  

PubMed

Poly(ethylene glycol) stabilized colloidal silver nanoparticles were prepared using the reductive potency of the aqueous extract of Thuja occidentalis leaves under ambient conditions. The nanoparticles were well dispersed within a narrow size spectrum (7-14 nm) and displayed characteristic surface plasmon resonance peak at around 420 nm and Bragg's reflection planes of fcc structure. MTT assay revealed the dose-dependent cytocompatibility and toxicity of the nanoparticles with the L929 normal cell line. On the other hand, the antiproliferative action of the nanoparticles was evaluated on HeLa cell (cancerous cells) line. Fluorescence and phase contrast microscopic imaging indicated the appearance of multinucleate stages with aggregation and nuclear membrane disruption of the HeLa cells post treatment with the nanoparticles. The interaction at the prokaryotic level was also assessed via differential antibacterial efficacy against Staphylococcus aureus (MTCC 3160) and Escherichia coli (MTCC 40). Under these perspectives, it is also necessary to observe the environmental impact of the prepared silver nanoparticles. Hence, the dose dependent toxicity of silver nanoparticles was evaluated upon the earthworm species Eisenia fetida. Neither the survival nor the reproduction was affected by the addition of silver nanoparticles up to 1000 ppm. Thus these 'green' silver nanoparticles have promising potential as future materials. PMID:23352940

Barua, Shaswat; Konwarh, Rocktotpal; Bhattacharya, Satya Sundar; Das, Pallabi; Devi, K Sanjana P; Maiti, Tapas K; Mandal, Manabendra; Karak, Niranjan

2013-05-01

167

Characterization and antimicrobial activity of silver nanoparticles prepared by a thermal decomposition technique  

NASA Astrophysics Data System (ADS)

Recently, there has been an increasing need of efficient synthetic protocols using eco-friendly conditions including low costs and green chemicals for production of metal nanoparticles. In this work, silver nanoparticles (silver NPs) with average particle size about 10 nm were synthesized by using a thermal decomposition technique. Unlike the colloidal chemistry method, the thermal decomposition method developed has advantages such as the high crystallinity, single-reaction synthesis, and easy dispersion ability of the synthesized NPs in organic solvents. In a modified synthesis process, we used sodium oleate as a capping agent to modify the surface of silver NPs because the oleate has a C18 tail with a double bond in the middle, therefore, forming a kink which is to be effective for aggregative stability. Importantly, the as-synthesized silver NPs have demonstrated strong antimicrobial effects against various bacteria and fungi strains. Electron microscopic studies reveal physical insights into the interaction and bactericidal mechanism between the prepared silver NPs and tested bacteria in question. The observed excellent antibacterial and antifungal activity of the silver NPs make them ideal for disinfection and biomedicine applications.

Tam, Le Thi; Phan, Vu Ngoc; Lan, Hoang; Thuy, Nguyen Thanh; Hien, Tran Minh; Huy, Tran Quang; Quy, Nguyen Van; Chinh, Huynh Dang; Tung, Le Minh; Tuan, Pham Anh; Lam, Vu Dinh; Le, Anh-Tuan

2013-11-01

168

Catalytically and biologically active silver nanoparticles synthesized using essential oil.  

PubMed

There are numerous reports on phytosynthesis of silver nanoparticles and various phytochemicals are involved in the reduction and stabilization. Pure explicit phytosynthetic protocol for catalytically and biologically active silver nanoparticles is of importance as it is an environmentally benign green method. This paper reports the use of essential oil of Myristica fragrans enriched in terpenes and phenyl propenes in the reduction and stabilization. FTIR spectra of the essential oil and the synthesized biogenic silver nanoparticles are in accordance with the GC-MS spectral analysis reports. Nanosilver is initially characterized by an intense SPR band around 420nm, followed by XRD and TEM analysis revealing the formation of 12-26nm sized, highly pure, crystalline silver nanoparticles. Excellent catalytic and bioactive potential of the silver nanoparticles is due to the surface modification. The chemocatalytic potential of nanosilver is exhibited by the rapid reduction of the organic pollutant, para nitro phenol and by the degradation of the thiazine dye, methylene blue. Significant antibacterial activity of the silver colloid against Gram positive, Staphylococcus aureus (inhibition zone - 12mm) and Gram negative, Escherichia coli (inhibition zone - 14mm) is demonstrated by Agar-well diffusion method. Strong antioxidant activity of the biogenic silver nanoparticles is depicted through NO scavenging, hydrogen peroxide scavenging, reducing power, DPPH and total antioxidant activity assays. PMID:24956490

Vilas, Vidya; Philip, Daizy; Mathew, Joseph

2014-11-11

169

Antibacterial activity and cell viability of hyaluronan fiber with silver nanoparticles.  

PubMed

Silver has been used since time immemorial in different chemical form to treat burns, wounds and several different infections caused by pathogenic bacteria, advancement of biological process of nanoparticles synthesis is evolving into a key area of nanotechnology. The current study deals with the green synthesis, characterization, and evaluation of the biological activity and cell viability of hyaluronan fibers with incorporated silver nanoparticles (HA-Ag NPs). Hyaluronan fiber was prepared by the dissolving of sodium hyaluronate (HA) in aqueous alkaline solution to prepare a transparent solution, which was used for the preparation of fibers by a wet-spinning technique. Consequently, hyaluronan fiber was used as capping and stabilizing agent for the preparation of fibers with silver nanoparticles. HA-Ag NPs were confirmed by transmission electron microscopy, dynamic light scattering, UV/VIS spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermal analysis, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. HA-Ag NPs showed high antibacterial activity of against Staphylococcus aureus and Escherichia coli. Cell viability tests indicated that hyaluronan, hyaluronan fibers and hyaluronan fibers with silver nanoparticles were non-toxic on the cell growth. Two different particles size of Ag NPs (10, 40 nm) had not any toxicity till the concentration limit. These tests were performed using mouse fibroblast cell line 3T3. PMID:23399144

Abdel-Mohsen, A M; Hrdina, Radim; Burgert, Ladislav; Abdel-Rahman, Rasha M; Hašová, Martina; Šmejkalová, Daniela; Kolá?, Michal; Pekar, M; Aly, A S

2013-02-15

170

Transformation of aromatic dyes using green synthesized silver nanoparticles.  

PubMed

Nowadays, increasing use of nanoproducts in area of human and environmental applications raises concern about safety aspects of nanoparticles synthesized using traditional physicochemical methods. Silver nanoparticles (AgNPs) synthesis at ambient parameters using latex of medicinally important plant Jatropha gossypifolia (J. gossypifolia) is reported in the present study. Potential of AgNPs in degradation of methylene blue and eosin B was also evaluated. Rapid formation of stable AgNPs was analyzed by visual color change from colorless to yellow-red after addition of latex in AgNO3 solution and by characteristic surface plasmon resonance (SPR) peak at 430 nm in UV-Vis spectroscopy. FT-IR analysis, protein coagulation test showed capping of proteins, flavonoids, terpenoids and polyphenols of latex on surface of AgNPs. FE-SEM, HR-TEM analysis revealed spherical shape of AgNPs. Narrow size range of AgNPs (5-40 nm) observed in HR-TEM analysis. EDS analysis confirms the presence of elemental silver while XRD revealed crystalline nature of AgNPs. Zeta potential of -21.4 mV indicates high stability of AgNPs. Effects of different parameters (pH, temperature, incubation time) on nanosynthesis were studied in the present study. Dye reduction studies were performed using UV-Vis spectroscopy, TLC, FT-IR and HPLC analysis showing decreased absorbance maxima of both dyes with respect to time, change in R f values, changes in wave number, transmittance, and retention time of dyes after AgNPs addition. The rate constant for methylene blue and eosin B reduction by AgNPs was found to be 0.062 and 0.022 min(-1). PMID:24525834

Borase, Hemant P; Patil, Chandrashekhar D; Salunkhe, Rahul B; Suryawanshi, Rahul K; Salunke, Bipinchandra K; Patil, Satish V

2014-08-01

171

Heavy-metal ion sensors using chitosan-capped gold nanoparticles  

Microsoft Academic Search

We report a novel strategy for using gold nanoparticles capped with chitosan for sensing ions of heavy metals. Acidic anions (glutamate ions in our case) are expected to cap the nanoparticle surfaces similar to conventional methods of stabilization of gold nanoparticles by citrate ions. The polycationic nature of chitosan enables attachment of the polymer to the negatively charged gold nanoparticle

A. Sugunan; C. Thanachayanont; J. Dutta; J. G. Hilborn

2005-01-01

172

Kinetic evolution studies of silver nanoparticles in a bio-based green synthesis process  

Microsoft Academic Search

Silver nanoparticles are being extensively studied due to their widespread applications and unique properties. In the present study, the growth kinetics of silver nanoparticles as synthesized on reduction of silver nitrate solution by aqueous extract of Azadirachta indica leaves was investigated. The formation of silver nanoparticles was preliminarily monitored by measuring the absorption maxima at different time intervals after adding

T. C. Prathna; N. Chandrasekaran; Ashok M. Raichur; Amitava Mukherjee

2011-01-01

173

Completely green synthesis of dextrose reduced silver nanoparticles, its antimicrobial and sensing properties.  

PubMed

We herein report the green synthesis of highly monodispersed, water soluble, stable and smaller sized dextrose reduced gelatin capped-silver nanoparticles (Ag-NPs) via an eco-friendly, completely green method. The synthesis involves the use of silver nitrate, gelatin, dextrose and water as the silver precursor, stabilizing agent, reducing agent and solvent respectively. By varying the reaction time, the temporal evolution of the growth, optical, antimicrobial and sensing properties of the as-synthesised Ag-NPs were investigated. The nanoparticles were characterized using UV-vis absorption spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HR-TEM). The absorption maxima of the as-synthesized materials at different reaction time showed characteristic silver surface plasmon resonance (SPR) peak. The as-synthesised Ag-NPs show better antibacterial efficacy than the antibiotics; ciproflaxin and imipenem against Pseudomonas aeruginosa with minimum inhibition concentration (MIC) of 6 ?g/mL, and better efficacy than imipenem against Escherichia coli with MIC of 10 ?g/mL. The minimum bactericidal concentration (MBC) of the as-synthesised Ag-NPs is 12.5 ?g/mL. The sensitivity of the dextrose reduced gelatin-capped Ag-NPs towards hydrogen peroxide indicated that the sensor has a very good sensitivity and a linear response over wide concentration range of 10(-1)-10(-6)M H2O2. PMID:24721103

Mohan, Sneha; Oluwafemi, Oluwatobi S; George, Soney C; Jayachandran, V P; Lewu, Francis B; Songca, Sandile P; Kalarikkal, Nandakumar; Thomas, Sabu

2014-06-15

174

Investigation of silver nanoparticles synthesis using aminated ?-cyclodextrin.  

PubMed

Aminated ?-cyclodextrin was prepared through the reaction of 2-chloroethylamine with ?-cyclodextrin. The preparation was carried out under different conditions (time, temperature, concentration of NaOH, and concentration of 2-chloroethylamine). The aminated ?-cyclodextrin was used as reducing and stabilizing agent for the preparation of silver nanoparticles from AgNO?. Factors (pH, temperature, time, extent of amination and concentration of aminated ?-cyclodextrin) affecting the preparation of silver nanoparticles were studied. The prepared silver nanoparticles were evaluated by UV-visible spectral analysis and transmission electron microscopy (TEM). The results obtained indicate that the optimum conditions for preparation of silver nanoparticles with size ranged from 1 to 9 nm could be produced using 0.6 g ?-cyclodextrin derivative, 0.1 M AgNO? at pH 12, 70 °C for 20 min. PMID:24750595

Abou-Okeil, A; Amr, A; Abdel-Mohdy, F A

2012-06-01

175

Silver Nanoparticles Part 1: Synthesis and Spectroscopy  

NSDL National Science Digital Library

The NACK Center is an organization committed to supporting two âÂÂyear degree programs in micro and nanotechnology. The center offers online educational material for curriculum enhancement in this subject field. One of these resources is a lab documentation focusing on the topic of silver nanoparticles. The lab is "designed for an advanced chemistry class, but may also be done with first year student. Prior experience with spectroscopy is recommended.â The lesson includes objectives, sample solution preparations, and sample data and calculations. Overall, the objectives of this lesson are to demonstrate the use of a spectrophotometer, the observation of nanoscale physical properties and conversion of different unit measurements. The site requires a free log-in for access to the material.

2010-03-31

176

Synthesis and characterization of silver nanoparticles in AOT microemulsion system  

Microsoft Academic Search

Colloidal silver nanoparticles have been synthesized in water-in-oil microemulsion using silver nitrate solubilized in the water core of one microemulsion as source of silver ions, hydrazine hydrate solubilized in the water core of another microemulsion as reducing agent, dodecane as the oil phase, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as the surfactant. The UV–vis absorption spectra and transmission electron microscopy (TEM) have

Wanzhong Zhang; Xueliang Qiao; Jianguo Chen

2006-01-01

177

Preparation of inorganic silica nanofibers containing silver nanoparticles  

Microsoft Academic Search

Silica nanofibers containing silver nanoparticles were successfully prepared using sol-gel chemistry and electro-spinning\\u000a technique. Solution of tetraethly orthosilicate in ethanol containing silver nitrate was aged to have sufficient viscosity\\u000a and electrospun to form nanofibers. Upon thermal treatment, the gelation reaction between silanols was completed in the prepared\\u000a silica nanofibers, and at the same time, silver ions in the nanofiber changed

Kyung Dan Min; Ji Ho Youk; Young-Je Kwark; Won Ho Park

2007-01-01

178

Label-free immunosensor based on gold nanoparticle silver enhancement  

Microsoft Academic Search

A label-free immunosensor for the sensitive detection of human immunoglobulin G (IgG) was prepared based on gold nanoparticle–silver enhancement detection with a simple charge-coupled device (CCD) detector. The gold nanoparticles, which were used as nuclei for the deposit of metallic silver and also for the adsorption of antibodies, were immobilized into wells of a 9-well chip. With the addition of

Minghui Yang; Cunchang Wang

2009-01-01

179

Silver nanoprism enhanced fluorescence in YVO4:Eu3+ nanoparticles.  

PubMed

Silver nanoprisms of different sizes influence fluorescence enhancement in YVO4:Eu(3+) nanoparticles to various degrees under excitation of green light (532 nm). The local field generated by silver nanoprisms and their dimers is simulated through the FDTD method and a direct correlation with fluorescence enhancement is established. PMID:24013681

Buch, Zubair; Kumar, Vineet; Mamgain, Hitesh; Chawla, Santa

2013-10-21

180

Antimicrobial properties of hydrated cellulose membranes with silver nanoparticles.  

PubMed

Microbial cellulose membranes have attracted a great deal of attention as novel wound-dressing materials, especially for the healing of skin burns and chronic wounds, because of their high water holding capacity and biocompatibility. However, the high humidity around the wound sometimes allows the growth of bacteria, as well as the regeneration of the tissue. In this study, silver nanoparticles were incorporated into the cellulose membranes via a chemical reduction method using a silver salt, silver nitrate (AgNO(3)) and a reducing agent, sodium borohydride (NaBH(4)). The silver nanoparticles were evenly adsorbed on the overall surface of the cellulose nanofibrils without any local aggregation and had a spherical shape with uniform size (8+/-2 nm) which allowed them to show antimicrobial properties. The interaction between the oxygen in cellulose and silver nanoparticles resulted in the stable adsorption of the silver nanoparticles on cellulose nanofibrils. The cellulose membrane with silver nanoparticles exhibited an antimicrobial activity of more than 99.99% against Escherichia coli and Staphylococcus aureus, so that it could be used as an antimicrobial wound-dressing material for chronic wounds and burns. PMID:19192358

Jung, Rira; Kim, Yeseul; Kim, Hun-Sik; Jin, Hyoung-Joon

2009-01-01

181

Rapid biological synthesis of silver nanoparticles using plant leaf extracts.  

PubMed

Five plant leaf extracts (Pine, Persimmon, Ginkgo, Magnolia and Platanus) were used and compared for their extracellular synthesis of metallic silver nanoparticles. Stable silver nanoparticles were formed by treating aqueous solution of AgNO(3) with the plant leaf extracts as reducing agent of Ag(+) to Ag(0). UV-visible spectroscopy was used to monitor the quantitative formation of silver nanoparticles. Magnolia leaf broth was the best reducing agent in terms of synthesis rate and conversion to silver nanoparticles. Only 11 min was required for more than 90% conversion at the reaction temperature of 95 degrees C using Magnolia leaf broth. The synthesized silver nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and particle analyzer. The average particle size ranged from 15 to 500 nm. The particle size could be controlled by changing the reaction temperature, leaf broth concentration and AgNO(3) concentration. This environmentally friendly method of biological silver nanoparticles production provides rates of synthesis faster or comparable to those of chemical methods and can potentially be used in various human contacting areas such as cosmetics, foods and medical applications. PMID:18438688

Song, Jae Yong; Kim, Beom Soo

2009-01-01

182

Antimicrobial activity and physical characterization of silver nanoparticles green synthesized using nitrate reductase from Fusarium oxysporum.  

PubMed

Nanostructures from natural sources have received major attention due to wide array of biological activities and less toxicity for humans, animals, and the environment. In the present study, silver nanoparticles were successfully synthesized using a fungal nitrate reductase, and their biological activity was assessed against human pathogenic fungi and bacteria. The enzyme was isolated from Fusarium oxysporum IRAN 31C after culturing on malt extract-glucose-yeast extract-peptone (MGYP) medium. The enzyme was purified by a combination of ultrafiltration and ion exchange chromatography on DEAE Sephadex and its molecular weight was estimated by gel filtration on Sephacryl S-300. The purified enzyme had a maximum yield of 50.84 % with a final purification of 70 folds. With a molecular weight of 214 KDa, it is composed of three subunits of 125, 60, and 25 KDa. The purified enzyme was successfully used for synthesis of silver nanoparticles in a way dependent upon NADPH using gelatin as a capping agent. The synthesized silver nanoparticles were characterized by X-ray diffraction, dynamic light scattering spectroscopy, and transmission and scanning electron microscopy. These stable nonaggregating nanoparticles were spherical in shape with an average size of 50 nm and a zeta potential of -34.3. Evaluation of the antimicrobial effects of synthesized nanoparticles by disk diffusion method showed strong growth inhibitory activity against all tested human pathogenic fungi and bacteria as evident from inhibition zones that ranged from 14 to 25 mm. Successful green synthesis of biologically active silver nanoparticles by a nitrate reductase from F. oxysporum in the present work not only reduces laborious downstream steps such as purification of nanoparticle from interfering cellular components, but also provides a constant source of safe biologically-active nanomaterials with potential application in agriculture and medicine. PMID:24610039

Gholami-Shabani, Mohammadhassan; Akbarzadeh, Azim; Norouzian, Dariush; Amini, Abdolhossein; Gholami-Shabani, Zeynab; Imani, Afshin; Chiani, Mohsen; Riazi, Gholamhossein; Shams-Ghahfarokhi, Masoomeh; Razzaghi-Abyaneh, Mehdi

2014-04-01

183

Studies on the Surface Interaction and Dispersity of Silver Nanoparticles in Organic Solvents  

NASA Astrophysics Data System (ADS)

Silver nanoparticles with different sizes have been prepared by microemulsion and have been surface-modified with C12H25SH. Electron spin resonance results indicate that there exist some kinds of surface local paramagnetic sites in capped Ag nanoparticles, which leads to the relation between electron spin resonance parameters and particle size deviating from Kawabata's description. There is a strong interaction between nanosilver and chloroform. The smaller the particles, the stronger the interaction. Transmission electron microscopy and ultravilolet-visible absorption spectra confirmed that Ag nanoparticles are well dispersed in chloroform, implying that a good dispersity of Ag nanoparticles in polymers could be obtained by means of solution mixing by using chloroform as the solvent.

Zeng, Rong; Rong, Min-Zhi; Zhang, Ming-Qiu; Zeng, Han-Min

2000-09-01

184

Silver ion mediated shape control of platinum nanoparticles: Removal of silver by selective etching leads to increased catalytic activity  

SciTech Connect

A procedure has been developed for the selective etching of Ag from Pt nanoparticles of well-defined shape, resulting in the formation of elementally-pure Pt cubes, cuboctahedra, or octahedra, with a largest vertex-to-vertex distance of {approx}9.5 nm from Ag-modified Pt nanoparticles. A nitric acid etching process was applied Pt nanoparticles supported on mesoporous silica, as well as nanoparticles dispersed in aqueous solution. The characterization of the silica-supported particles by XRD, TEM, and N{sub 2} adsorption measurements demonstrated that the structure of the nanoparticles and the mesoporous support remained conserved during etching in concentrated nitric acid. Both elemental analysis and ethylene hydrogenation indicated etching of Ag is only effective when [HNO{sub 3}] {ge} 7 M; below this concentration, the removal of Ag is only {approx}10%. Ethylene hydrogenation activity increased by four orders of magnitude after the etching of Pt octahedra that contained the highest fraction of silver. High-resolution transmission electron microscopy of the unsupported particles after etching demonstrated that etching does not alter the surface structure of the Pt nanoparticles. High [HNO{sub 3}] led to the decomposition of the capping agent, polyvinylpyrollidone (PVP); infrared spectroscopy confirmed that many decomposition products were present on the surface during etching, including carbon monoxide.

Grass, Michael E.; Yue, Yao; Habas, Susan E.; Rioux, Robert M.; Teall, Chelsea I.; Somorjai, G.A.

2008-01-09

185

Silver nanoparticle applications and human health.  

PubMed

Nanotechnology is rapidly growing with nanoparticles produced and utilized in a wide range of commercial products throughout the world. For example, silver nanoparticles (Ag NP) are used in electronics, bio-sensing, clothing, food industry, paints, sunscreens, cosmetics and medical devices. These broad applications, however, increase human exposure and thus the potential risk related to their short- and long-term toxicity. A large number of in vitro studies indicate that Ag NPs are toxic to the mammalian cells derived from skin, liver, lung, brain, vascular system and reproductive organs. Interestingly, some studies have shown that this particle has the potential to induce genes associated with cell cycle progression, DNA damage and apoptosis in human cells at non-cytotoxic doses. Furthermore, in vivo bio-distribution and toxicity studies in rats and mice have demonstrated that Ag NP administered by inhalation, ingestion or intra-peritoneal injection were subsequently detected in blood and caused toxicity in several organs including brain. Moreover, Ag NP exerted developmental and structural malformations in non-mammalian model organisms typically used to elucidate human disease and developmental abnormalities. The mechanisms for Ag NP induced toxicity include the effects of this particle on cell membranes, mitochondria and genetic material. This paper summarizes and critically assesses the current studies focusing on adverse effects of Ag NPs on human health. PMID:20719239

Ahamed, Maqusood; Alsalhi, Mohamad S; Siddiqui, M K J

2010-12-14

186

Anti-proliferative activity of silver nanoparticles  

PubMed Central

Background Nanoparticles possess exceptional physical and chemical properties which led to rapid commercialisation. Silver nanoparticles (Ag-np) are among the most commercialised nanoparticles due to their antimicrobial potential. Ag-np based cosmetics, therapeutic agents and household products are in wide use, which raised a public concern regarding their safety associated with human and environmental use. No safety regulations are in practice for the use of these nanomaterials. The interactions of nanomaterials with cells, uptake mechanisms, distribution, excretion, toxicological endpoints and mechanism of action remain unanswered. Results Normal human lung fibroblasts (IMR-90) and human glioblastoma cells (U251) were exposed to different doses of Ag-nps in vitro. Uptake of Ag-nps occurred mainly through endocytosis (clathrin mediated process and macropinocytosis), accompanied by a time dependent increase in exocytosis rate. The electron micrographs revealed a uniform intracellular distribution of Ag-np both in cytoplasm and nucleus. Ag-np treated cells exhibited chromosome instability and mitotic arrest in human cells. There was efficient recovery from arrest in normal human fibroblasts whereas the cancer cells ceased to proliferate. Toxicity of Ag-np is mediated through intracellular calcium (Ca2+) transients along with significant alterations in cell morphology and spreading and surface ruffling. Down regulation of major actin binding protein, filamin was observed after Ag-np exposure. Ag-np induced stress resulted in the up regulation of metallothionein and heme oxygenase -1 genes. Conclusion Here, we demonstrate that uptake of Ag-np occurs mainly through clathrin mediated endocytosis and macropinocytosis. Our results suggest that cancer cells are susceptible to damage with lack of recovery from Ag-np-induced stress. Ag-np is found to be acting through intracellular calcium transients and chromosomal aberrations, either directly or through activation of catabolic enzymes. The signalling cascades are believed to play key roles in cytoskeleton deformations and ultimately to inhibit cell proliferation.

AshaRani, PV; Hande, M Prakash; Valiyaveettil, Suresh

2009-01-01

187

Formation of silver nanoparticles on polypropylene microfibrous carriers  

NASA Astrophysics Data System (ADS)

Methods of physical and numerical experiments are used to investigate formation of quantum dissipative silver nanostructures on polypropylene microfibrous condensed-state carriers under two-stage activation by UV- and microwave radiation. For these two nanoprocessing stages, two different mechanisms of quantum activated silver nanoparticle relaxation are suggested, including dissipation of their energy into the polymeric matrix through the exciton femtosecond and phonon picosecond channels. A comparison of the results of mathematical modeling and physical experiments testifies to the adequacy of these models to the physical processes of self-assembly and self-organization of polymeric biomimetic fibrous material modified by silver nanoparticles.

Zhukovsky, M. S.; Lysak, I. A.; Lysak, G. V.; Vazhenin, S. V.; Malinovskaya, T. D.; Beznosjuk, S. A.

2011-12-01

188

Cellular oxido-reductive proteins of Chlamydomonas reinhardtii control the biosynthesis of silver nanoparticles  

PubMed Central

Background Elucidation of molecular mechanism of silver nanoparticles (SNPs) biosynthesis is important to control its size, shape and monodispersity. The evaluation of molecular mechanism of biosynthesis of SNPs is of prime importance for the commercialization and methodology development for controlling the shape and size (uniform distribution) of SNPs. The unicellular algae Chlamydomonas reinhardtii was exploited as a model system to elucidate the role of cellular proteins in SNPs biosynthesis. Results The C. reinhardtii cell free extract (in vitro) and in vivo cells mediated synthesis of silver nanoparticles reveals SNPs of size range 5 ± 1 to 15 ± 2 nm and 5 ± 1 to 35 ± 5 nm respectively. In vivo biosynthesized SNPs were localized in the peripheral cytoplasm and at one side of flagella root, the site of pathway of ATP transport and its synthesis related enzymes. This provides an evidence for the involvement of oxidoreductive proteins in biosynthesis and stabilization of SNPs. Alteration in size distribution and decrease of synthesis rate of SNPs in protein-depleted fractions confirmed the involvement of cellular proteins in SNPs biosynthesis. Spectroscopic and SDS-PAGE analysis indicate the association of various proteins on C. reinhardtii mediated in vivo and in vitro biosynthesized SNPs. We have identified various cellular proteins associated with biosynthesized (in vivo and in vitro) SNPs by using MALDI-MS-MS, like ATP synthase, superoxide dismutase, carbonic anhydrase, ferredoxin-NADP+ reductase, histone etc. However, these proteins were not associated on the incubation of pre-synthesized silver nanoparticles in vitro. Conclusion Present study provides the indication of involvement of molecular machinery and various cellular proteins in the biosynthesis of silver nanoparticles. In this report, the study is mainly focused towards understanding the role of diverse cellular protein in the synthesis and capping of silver nanoparticles using C. reinhardtii as a model system.

2011-01-01

189

Green synthesis of silver nanoparticles from Gloriosa superba L. leaf extract and their catalytic activity.  

PubMed

The present work focuses the use of aqueous extract of Gloriosa superba Linn. (Glory Lily) for producing silver nanoparticles (AgNPs) from silver nitrate aqueous solution. Phytochemical analysis of the extract revealed the presence of alkaloid, amino acids, carbohydrates and proteins in the extract and they serve as effective reducing and capping agents for converting silver nitrate to silver nanoparticles. The nanoparticles were characterised by UV (Ultra violet), FT-IR (Fourier Transform Infrared), XRD (X-ray diffraction), TEM (Transmission Electron Microscope) SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-ray), and PL (Photoluminescence) studies. Moreover, the catalytic activity of synthesized AgNPs in the reduction of methylene blue was studied by UV-vis spectrophotometer. The synthesized AgNPs are observed to have a good catalytic activity on the reduction of methylene blue by G. superba extract which is confirmed by the decrease in absorbance maximum values of methylene blue with respect to time using UV-vis spectrophotometer. PMID:23860402

Ashokkumar, S; Ravi, S; Velmurugan, S

2013-11-01

190

Green synthesis of silver nanoparticles from Gloriosa superba L. leaf extract and their catalytic activity  

NASA Astrophysics Data System (ADS)

The present work focuses the use of aqueous extract of Gloriosa superba Linn. (Glory Lily) for producing silver nanoparticles (AgNPs) from silver nitrate aqueous solution. Phytochemical analysis of the extract revealed the presence of alkaloid, amino acids, carbohydrates and proteins in the extract and they serve as effective reducing and capping agents for converting silver nitrate to silver nanoparticles. The nanoparticles were characterised by UV (Ultra violet), FT-IR (Fourier Transform Infrared), XRD (X-ray diffraction), TEM (Transmission Electron Microscope) SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-ray), and PL (Photoluminescence) studies. Moreover, the catalytic activity of synthesized AgNPs in the reduction of methylene blue was studied by UV-vis spectrophotometer. The synthesized AgNPs are observed to have a good catalytic activity on the reduction of methylene blue by G. superba extract which is confirmed by the decrease in absorbance maximum values of methylene blue with respect to time using UV-vis spectrophotometer.

Ashokkumar, S.; Ravi, S.; Velmurugan, S.

2013-11-01

191

Oxide and hydrogen capped ultrasmall blue luminescent Si nanoparticles  

SciTech Connect

We dispersed electrochemical etched silicon into a colloid of ultrasmall ultrabright Si nanoparticles. Direct imaging using transmission electron microscopy shows particles of {approx}1 nm in diameter, and infrared and electron photospectroscopy show that they are passivated with hydrogen. Under 350 nm excitation, the luminescence is dominated by an extremely strong blue band at 390 nm. We replace hydrogen by a high-quality ultrathin surface oxide cap by self-limiting oxidation in H{sub 2}O{sub 2}. Upon capping, the excitation efficiency drops, but only by a factor of 2, to an efficiency still two-fold larger than that of fluorescein. Although of slightly lower brightness, capped Si particles have superior biocompatability, an important property for biosensing applications. (c) 2000 American Institute of Physics.

Belomoin, Gennadiy [Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, Illinois 61801 (United States)] [Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, Illinois 61801 (United States); Therrien, Joel [Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, Illinois 61801 (United States)] [Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, Illinois 61801 (United States); Nayfeh, Munir [Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, Illinois 61801 (United States)] [Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, Illinois 61801 (United States)

2000-08-07

192

Biosynthesis, characterization and antibacterial studies of silver nanoparticles using pods extract of Acacia auriculiformis.  

PubMed

The present study reports an environmental friendly method for the synthesis of silver nanoparticles (Ag NPs) using an aqueous extract of Acacia auriculiformis that acts as reducing agent as well as capping agent. The obtained NPs were characterized by UV-vis absorption spectroscopy and showed a sharp surface plasmon absorption band at ?400nm. Fourier transform infrared spectroscopy (FTIR) showed nanoparticles were capped with plant compounds. Transmission electron microscopy (TEM) showed that the particles were spherical in nature with diameter ranging from 20 to 150nm depending on the pH of the solution. The as-synthesized Ag NPs showed antibacterial activity against both Gram negative and Gram positive bacteria with more efficacy against Gram negative bacteria. PMID:24727170

Nalawade, Pradnya; Mukherjee, Poulomi; Kapoor, Sudhir

2014-08-14

193

Biosynthesis, characterization and antibacterial studies of silver nanoparticles using pods extract of Acacia auriculiformis  

NASA Astrophysics Data System (ADS)

The present study reports an environmental friendly method for the synthesis of silver nanoparticles (Ag NPs) using an aqueous extract of Acacia auriculiformis that acts as reducing agent as well as capping agent. The obtained NPs were characterized by UV-vis absorption spectroscopy and showed a sharp surface plasmon absorption band at ?400 nm. Fourier transform infrared spectroscopy (FTIR) showed nanoparticles were capped with plant compounds. Transmission electron microscopy (TEM) showed that the particles were spherical in nature with diameter ranging from 20 to 150 nm depending on the pH of the solution. The as-synthesized Ag NPs showed antibacterial activity against both Gram negative and Gram positive bacteria with more efficacy against Gram negative bacteria.

Nalawade, Pradnya; Mukherjee, Poulomi; Kapoor, Sudhir

194

Environmental and Human Health Risks of Aerosolized Silver Nanoparticles  

Microsoft Academic Search

Silver nanoparticles (AgNPs) are gaining attention from the academic and regulatory communities, not only because of their antimicrobial effects and subsequent product applications, but also because of their potential health and environmental risks. Whereas AgNPs in the aqueous phase are under intensive study, those in the atmosphere have been largely overlooked, although it is well established that inhalation of nanoparticles

Marina E. Quadros; Linsey C. Marr; Krzysztof Pikon´; Krzysztof Gaska; Lingjuan Wang; Edgar Oviedo-Rondon; John Small; Zifei Liu; Brian Sheldon; Gerald Havenstein; C. Williams; Di Tian; Daniel Cohan; Sergey Napelenok; Michelle Bergin; Yongtao Hu; Michael Chang; Armistead Russell; Ye Xu; Guohe Huang; Xiaosheng Qin; Kuo-Pin Yu; Grace Lee; Guo-Hao Huang; Prabhakar Sharma; Tjalfe Poulsen; William Vizuete; Leiran Biton; Harvey Jeffries; Evan Couzo; Yi-Chi Chien; Chenju Liang; Shou-Heng Liu; Shu-Hua Yang; Maciej Kryza; Malgorzata Werner; Marek Blas; Anthony Dore; Mieczyslaw Sobik; Daniel Olsen; Morgan Kohls; Gregg Arney; Kaushlendra Singh; L. Risse; K. C. Das; John Worley; Sidney Thompson; Bryan Comer; James Corbett; J. Hawker; Karl Korfmacher; Earl Lee; Chris Prokop; James Winebrake

2010-01-01

195

Mechanically interlocked gold and silver nanoparticles using metallosupramolecular catenane chemistry.  

PubMed

We have employed the toolbox of metallosupramolecular chemistry to mechanically interlock gold and silver nanoparticles. A specifically designed PEGthiol-functionalized bis(phenanthroline)copper(I) complex acts to 'catenate' the nanoparticles. The interlocked assemblies were characterised by three complementary techniques: DLS, SERS and TEM. PMID:21264434

Otter, Carl A; Patty, Philipus J; Williams, Martin A K; Waterland, Mark R; Telfer, Shane G

2011-03-01

196

Novel technique for fine structuring in glass containing silver nanoparticles  

Microsoft Academic Search

Direct current (dc) electric field assisted dissolution of silver nanoparticles embedded in glass is presented. Using the presented technique 125, 600 and 1800 lines of embedded metallic structures per millimeter are easily produced. ©2005 Optical Society of America OCIS codes: Lately composite materials containing metal nanoparticles have increasingly found various applications in different fields of science and technology (1-3). In

Amin Abdolvand; Alexander Podlipensky; Gerhard Seifert; Peter G. Kazansky; Heinrich Graener

197

Optical properties of organic and inorganic capped CdS nanoparticles and the effects of x-ray irradiation on organic capped CdS nanoparticles  

SciTech Connect

In this article, the authors report synthesis of CdS nanoparticles using a simple, inexpensive and straightforward chemical colloidal method using organic and inorganic capping agents. 1-6 hexanedithiol, mercaptoethanol, thioglycerol, tetraethyl orthosilicate, and tetraethyl orthotitaniate are used as the capping agents. The optical absorption spectra of CdS nanoparticles synthesized using the same parameters are found to depend on the nature of capping agents. The infrared absorption measurements provided important information about the nature of bonding. The optical studies on effect of x-ray irradiation on thioglycerol-capped CdS nanoparticle are also discussed.

Hullavarad, Nilima V.; Hullavarad, Shiva S. [Office of Electronic Miniaturization, University of Alaska Fairbanks, Fairbanks, Alaska 99701 (United States)

2008-07-15

198

The Use of chitosan in The Formation of Silver Nanoparticles, Chitosanic Nanoparticles and Fibrous Structures  

NASA Astrophysics Data System (ADS)

Nanoscale materials have attracted much attention in the last two decades due to their unique properties. The size effect attains new chemical and physical properties to these materials. Nanoparticles and nanofiber are major component of nanomaterials and they have heavily investigated in the literature for different applications. Nanoparticles could be produced from both metals as well as polymers. Chitosan, which is a natural polymer, can be used as capping agent in the preparation of metallic nanoparticles and itself, can produce nanoparticles. The utilization of nanoparticles and nanofibers for wound dressing materials is a very popular approach. Acquiring antibacterial properties to the wound dressing materials could be obtained either by formulation of nanomaterials composites or direct chemical modification of the substance. To improve the antibacterial properties of chitosan two approaches were applied. First, is through the formulation of chitosan with silver nanoparticles and the formation of nanofiber mats. In this study, the concepts of green chemistry were applied and silver nanoparticles were prepared in high concentration using chitosan as a capping polymer and glucose as a reducing agent. Nanofiber mats of polyvinyl alcohol/chitosan/silvernanoparticles were produced via electrospinning. The antibacterial activity of these fibers shows bactericidal effect against E. coli at low concentrations of Ag-NPs. In the second approach, direct chemical modification of chitosan was performed by grafting of Iodoacetic acid to the amino group at carbon-2. The chemical structure of chitosan Iodoacetamide derivative (CIA) was confirmed by FTIR and H1-NMR. The derivative was amorphous and water soluble at neutral pH. The minimum inhibitory concentration of CIA, against E. coli, was 400ig/mL and the derivative was bacteriostatic after 4h of treatment. Nanofiber mats of polyvinyl alcohol/chitosan/chitosan Iodoacetamide were produced via electrospinning. The antibacterial testing of the nanofiber mats were performed according to AATCC-100 protocol. PVA/CS/CIA system was found to have superior antibacterial action over PVA/CS/thiolchitosan counterparts. In the last part of the thesis, chitosan nanoparticles were prepared; for the first time in the literature instead of Tripolyphosphate (TPP), via ionic crosslinking with hexametaphosphate (HMP). A systematic study was conducted to apply the chitosan/HMP nanoparticles as a hydrophilic drug carrier for protein drugs. Chitosan/HMP systems were found to be unstable in the acidic medium. The optimum complexation conditions were established as pH 5 and the nanoparticles showed better stability at 21 days. Chitosan concentration plays an important role in improving particles stability by increasing zeta potential; however, it adversely affects the particles size. BSA loading capacity of chitosan/HMP was higher, 96.3%, than that of TPP, 91.87%, equivalents due to larger average size.

Abdelgawad, Abdelrahman Mohamed

199

Size-dependent structure of silver nanoparticles under high pressure  

SciTech Connect

Silver noble metal nanoparticles that are<10 nm often possess multiply twinned grains allowing them to adopt shapes and atomic structures not observed in bulk materials. The properties exhibited by particles with multiply twinned polycrystalline structures are often far different from those of single-crystalline particles and from the bulk. I will present experimental evidence that silver nanoparticles<10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. Results for nanoparticles in the intermediate size range of 5 to 10 nm suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. I propose a mechanism for this transitiion that considers the bond-length distribution in idealized multiply twinned icosahedral particles. Results for nanoparticles of 3.9 nm suggest a reversible linear pressure-dependent orthorhombic distortion. This distortion is interpreted in the context of idealized decahedral particles. In addition, given these size-dependent measurements of silver nanoparticle compression with pressure, we have constructed a pressure calibration curve. Encapsulating these silver nanoparticles in hollow metal oxide nanospheres then allows us to measure the pressure inside a nanoshell using x-ray diffraction. We demonstrate the measurement of pressure gradients across nanoshells and show that these nanoshells have maximum resolved shear strengths on the order of 500 MPa to IGPa.

Koski, Kristie Jo

2008-12-31

200

Agricultural waste Annona squamosa peel extract: Biosynthesis of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Development of reliable and eco-friendly process for the synthesis of metallic nanoparticles is an important step in the field of application of nanotechnology. We have developed modern method by using agriculture waste to synthesize silver nanoparticles by employing an aqueous peel extract of Annona squamosa in AgNO3. Controlled growth of silver nanoparticles was formed in 4 h at room temperature (25 °C) and 60 °C. AgNPs were irregular spherical in shape and the average particle size was about 35 ± 5 nm and it is consistent with particle size obtained by XRD Scherer equation.

Kumar, Rajendran; Roopan, Selvaraj Mohana; Prabhakarn, Arunachalam; Khanna, Venkatesan Gopiesh; Chakroborty, Subhendu

2012-05-01

201

Laser based fabrication of chitosan mediated silver nanoparticles  

NASA Astrophysics Data System (ADS)

We report fabrication of silver nanoparticles (Ag NPs) by laser ablation technique in different concentrations of aqueous chitosan solution. The ablation process of silver plate was carried out by using a nanosecond Q-switched Nd:YAG pulsed laser and the characterization of Ag NPs was done by Transmission electron microscopy, UV-Vis spectroscopy, and X-ray diffraction. UV-visible plasmon absorption spectra revealed that the formation efficiency as well as the stability of nanoparticles was increased by addition of chitosan. On the other hand, the size decrement of nanoparticles was more remarkable in the higher chitosan concentration.

Zamiri, Reza; Azmi, B. Z.; Naseri, Mahmoud Goodarz; Ahangar, Hossein Abbastabar; Darroudi, Majid; Nazarpour, Forough Kalaei

2011-10-01

202

Core-shell silver nanoparticles for optical labeling of cells.  

PubMed

Silver nanoparticles have been modified with self-assembled monolayers of hydroxyl-terminated long chain thiols and encapsulated with a silica shell. The resulting core-shell nanoparticles were used as optical labels for cell analysis using flow cytometry and microscopy. The excitation of plasmon resonances in nanoparticles results in strong depolarized scattering of visible light, permitting detection at the single nanoparticle level. The nanoparticles were modified with neutravidin via epoxide-azide coupling chemistry, to which biotinylated antibodies targeting cell surface receptors were bound. The nanoparticle labels exhibited long-term stability in solutions with high salt concentrations without aggregation or silver etching. Labeled cells exhibited two orders of magnitude enhancement of the scattering intensity compared with unlabeled cells. PMID:24755004

Dukes, Kyle D; Christensen, Kenneth A; Chumanov, George

2014-08-01

203

Complexation of porphyrins with silver and zeolite nanoparticles  

NASA Astrophysics Data System (ADS)

It is known that nanoparticles of colloidal silver and zeolites due to the porosity have an extremely large specific surface, which is an order of magnitude increases their sorption capacity. Previously we synthesized a set of water-soluble cationic porphyrins and metalloporphyrins and in the laboratory in vitro had shown their high effectiveness against the various cancer cell lines, and against a variety of microorganisms. The aim of this work was to study of processes sorption/desorption of porphyrins on nanoparticles of silver and zeolites. The interaction of cationic porphyrins with silver nanoparticles of 20 nm diameter was studied in the visible spectrum, in the range 350-800 nm. Investigation of sorption dynamics of porphyrins in the silver nanoparticles using two porphyrins: a) meso-tetra (4-N-butyl pyridyl) porphyrin (TBut4PyP), b) Ag-TBut4PyP, as well as of photosensitizer Al-phthalocyanine was carried out. Analysis of the dynamics of change in the absorption spectra for porphyrins TBut4PyP, Ag-TBut4PyP, Zn-TBut4PyP and Zn-TOEt4PyP by adding of nanoparticles of colloidal silver and zeolites leads to the conclusions: 1. nanoparticles of colloidal silver and zeolites are promising adsorbents for cationic porphyrins (sorption of 55-60% and 90-95%, respectively); 2. sorbents stable long (at least 24 hours) keeps the cationic porphyrins; 3. on nanoparticles of colloidal silver and zeolites an anionic and neutral porphyrins not be adsorbed or adsorbed bad.

Gyulkhandanyan, Anna G.; Ghazaryan, Robert K.; Gasparyan, Vardan K.; Sargsyan, Hakob O.; Madoyan, Roza A.; Gyulkhandanyan, Aram G.; Paronyan, Marina H.; Stasheuski, Alexandr S.; Knyukshto, Valery N.; Dzhagarov, Boris M.; Gyulkhandanyan, Grigor V.

2013-05-01

204

In Vitro Toxicity of Silver Nanoparticles in Human Lung Epithelial Cells.  

National Technical Information Service (NTIS)

Nanotechnology is quickly becoming incorporated into everyday products and uses. Silver nanoparticles, specifically, are being used in commercial products, to include aerosols. The purpose of this research was to determine whether silver nanoparticles are...

C. R. Kearns

2009-01-01

205

Preparation of conducting silver paste with Ag nanoparticles prepared by e-beam irradiation  

NASA Astrophysics Data System (ADS)

Conducting silver paste was prepared by using Ag nanoparticles which were synthesized by e-beam irradiation method (from KAERI); its conductivity was comparatively determined with Ag nanoparticles which were prepared by thermolysis method (commercial). The silver nanoparticles with the diameter of approximately 150 nm size prepared by e-beam irradiation were mixed with glass frit and sintered for 1 h at 500 °C. It is presumably concluded that the wt% of silver nanoparticle, size distribution and homogenous dispersibility of Ag nanoparticles in the pastes are the critical factors for the high conductivity of the paste. Among the various wt% of silver nanoparticle in the conducting silver pastes, silver paste with 90 wt% of silver nanoparticle has the highest conductivity as 1.6×10 4 S cm -1. This conductivity value is 1.6 times higher than the Ag pastes which were prepared with silver nanoparticles obtained by thermolysis method.

Sohn, Jong Hwa; Pham, Long Quoc; Kang, Hyun Suk; Park, Ji Hyun; Lee, Byung Cheol; Kang, Young Soo

2010-11-01

206

Structural and morphological investigations of ?-cyclodextrin-coated silver nanoparticles.  

PubMed

This paper describes the synthesis of silver nanoparticles using an aqueous silver nitrate solution in the presence of glucose as a reducing agent, sodium hydroxide as a reaction catalyst and ?-CD as a stabilizer. The structure and the morphology associated to the stabilizing layer around the silver nanoparticles were investigated. Raman spectroscopy confirmed the nanoparticle surface modification by ?-CD, demonstrating the interaction between the ?-CD rim hydroxyl groups and the AgNP surface. Transmission electron microscopy images showed an average 28.0nm diameter pseudo-spherical nanoparticles. Apart from this, a novel characterization of the ?-CD layer surrounding the nanoparticles was carried out by using complementary analytical electron microscopy based on electron spectroscopy imaging in the transmission microscope. Mapping images revealed the presence of carbon and oxygen, demonstrating the existence of a uniform and interacting ?-CD layer covering the nanoparticles. The antibacterial activity was also investigated and the ?-CD-coated silver nanoparticles showed a promising bactericidal activity against the microorganism Escherichia coli. PMID:24780436

Andrade, Patricia Fernanda; de Faria, Andreia Fonseca; da Silva, Douglas Soares; Bonacin, Juliano Alves; Gonçalves, Maria do Carmo

2014-06-01

207

Inhibitory effects of silver nanoparticles on H1N1 influenza A virus in vitro  

Microsoft Academic Search

Silver nanoparticles have demonstrated efficient inhibitory activities against human immunodeficiency virus (HIV) and hepatitis B virus (HBV). However, the effects of silver nanoparticles against H1N1 influenza A virus remain unexplored. In this study, the interaction of silver nanoparticles with H1N1 influenza A virus was investigated. Silver nanoparticles with mean particle diameters of 10nm were prepared for the hemagglutination inhibition test,

Dong-xi Xiang; Qian Chen; Lin Pang; Cong-long Zheng

2011-01-01

208

Distribution of silver in rats following 28 days of repeated oral exposure to silver nanoparticles or silver acetate  

PubMed Central

Background The study investigated the distribution of silver after 28 days repeated oral administration of silver nanoparticles (AgNPs) and silver acetate (AgAc) to rats. Oral administration is a relevant route of exposure because of the use of silver nanoparticles in products related to food and food contact materials. Results AgNPs were synthesized with a size distribution of 14 ± 4 nm in diameter (90% of the nanoparticle volume) and stabilized in aqueous suspension by the polymer polyvinylpyrrolidone (PVP). The AgNPs remained stable throughout the duration of the 28-day oral toxicity study in rats. The organ distribution pattern of silver following administration of AgNPs and AgAc was similar. However the absolute silver concentrations in tissues were lower following oral exposure to AgNPs. This was in agreement with an indication of a higher fecal excretion following administration of AgNPs. Besides the intestinal system, the largest silver concentrations were detected in the liver and kidneys. Silver was also found in the lungs and brain. Autometallographic (AMG) staining revealed a similar cellular localization of silver in ileum, liver, and kidney tissue in rats exposed to AgNPs or AgAc. Using transmission electron microscopy (TEM), nanosized granules were detected in the ileum of animals exposed to AgNPs or AgAc and were mainly located in the basal lamina of the ileal epithelium and in lysosomes of macrophages within the lamina propria. Using energy dispersive x-ray spectroscopy it was shown that the granules in lysosomes consisted of silver, selenium, and sulfur for both AgNP and AgAc exposed rats. The diameter of the deposited granules was in the same size range as that of the administered AgNPs. No silver granules were detected by TEM in the liver. Conclusions The results of the present study demonstrate that the organ distribution of silver was similar when AgNPs or AgAc were administered orally to rats. The presence of silver granules containing selenium and sulfur in the intestinal wall of rats exposed to either of the silver forms suggests a common mechanism of their formation. Additional studies however, are needed to gain further insight into the underlying mechanisms of the granule formation, and to clarify whether AgNPs dissolve in the gastrointestinal system and/or become absorbed and translocate as intact nanoparticles to organs and tissues.

2011-01-01

209

Low temperature plasma sintering of silver nanoparticles  

NASA Astrophysics Data System (ADS)

The fabrication of flexible electronics using the deposition of solution-processed nanomaterials generally requires low-temperature post-processing to optimize functionality. We studied sintering of silver nanoparticle (AgNP) films on glass substrates by applying argon (Ar) plasma to achieve improved electrical conductivity. This process meets the low temperature processing requirements for standard low-cost polymeric flexible substrates. The relationship between plasma parameters (such as power and sintering time) versus sintering results (such as electrical sheet resistance, sintered structure depth, materials composition variation, and film nanostructure) is reported for 23 and 77 nm diameter AgNPs. In addition, plasma processing typically induces a small surface thermal effect. We monitored the surface temperatures of the AgNP films in-situ during plasma sintering. By sintering control groups at these monitored surface temperatures using a vacuum oven, we confirmed that the resistivity due to plasma sintering is less than that produced by thermal sintering. Our data show that, the measured lowest resistivities for plasma sintered AgNP films are about only 5 and 12 times greater than the bulk Ag resistivity for 23 and 77 nm, respectively.

Ma, Siyuan; Bromberg, Vadim; Liu, Liang; Egitto, Frank D.; Chiarot, Paul R.; Singler, Timothy J.

2014-02-01

210

Catalytic degradation of organic dyes using biosynthesized silver nanoparticles.  

PubMed

The green synthesis of metallic nanoparticles paved the way to improve and protect the environment by decreasing the use of toxic chemicals and eliminating biological risks in biomedical applications. Plant mediated synthesis of metal nanoparticles is gaining more importance owing to its simplicity, rapid rate of synthesis of nanoparticles and eco-friendliness. The present article reports an environmentally benign and unexploited method for the synthesis of silver nanocatalysts using Trigonella foenum-graecum seeds, which is a potential source of phytochemicals. The UV-visible absorption spectra of the silver samples exhibited distinct band centered around 400-440 nm. The major phytochemicals present in the seed extract responsible for the formation of silver nanocatalysts are identified using FTIR spectroscopy. The report emphasizes the effect of the size of silver nanoparticles on the degradation rate of hazardous dyes, methyl orange, methylene blue and eosin Y by NaBH4. The efficiency of silver nanoparticles as a promising candidate for the catalysis of organic dyes by NaBH4 through the electron transfer process is established in the present study. PMID:24210247

Vidhu, V K; Philip, Daizy

2014-01-01

211

Preparation of silver nanoparticles using tryptophan and its formation mechanism.  

PubMed

A non-toxic route was used for the preparation of silver nanoparticles using tryptophan (Trp) as reducing/stabilizing agent in the presence of cetyltrimethyl ammonium bromide (CTAB). Role of water soluble neutral polymer poly(vinylpyrrolidone) (PVP) has been studied on the growth of yellow colour silver nanoparticle formation. The synthesized nanostructures were characterized by UV-Visible absorption spectroscopy, transmission electron microscopy (TEM) by observing the size and distribution of silver nanoparticles. As the reaction proceeded, particles grew up to about 10 and 20 nm in the presence and absence of PVP, respectively, as determined by TEM. The formed nanoparticles showed the highest absorption plasmon band at 425 nm. Rate of silver sol formation increases with the [Trp], [CTAB] and [PVP], reaching a limiting value and then decreases with the increase in concentrations of these reagents. It was observed that nanoparticles are spherical, aggregated and poly dispersed in the absence and presence of PVP, respectively. On the basis of kinetic data, a suitable mechanism is proposed and discussed for the silver sol formation. PMID:20801004

Zaheer, Zoya; Malik, Maqsood Ahmad; Al-Nowaiser, F M; Khan, Zaheer

2010-12-01

212

Preparation of Silver Nanoparticles Incorporated Electrospun Polyurethane Nano-fibrous Mat for Wound Dressing  

Microsoft Academic Search

Polyurethane foam is currently used as an exudate absorptive wound dressing material. In this study silver (Ag) nanoparticles were incorporated into electrospun polyurethane (PU) nanofiber to enhance the antibacterial as well as wound healing properties. The electrospinning parameters were optimized for PU with and without silver nanoparticles. Silver nanoparticles were synthesized by aqueous and organic methods. The water absorption, antibacterial

Lakshmi R. Lakshman; K. T. Shalumon; Sreeja V. Nair; R. Jayakumar

2010-01-01

213

Antibacterial Nanofinishing of Cotton Fabrics Using Silver Nanoparticles via Simultaneous Synthesizing and Coating Process  

Microsoft Academic Search

This study describes the nanofinishing of cotton fabric using silver nanoparticles synthesized simultaneously in the presence of such a simple reducing agent. The silver nanoparticles are analyzed by scanning electron microscope image, which disclosed the attendance of silver nanoparticles on cotton fibers. The coated fabrics show antibacterial activity, which could render them of value in applications. Antibacterial tests against Staphylococcus

A. Shams Nateri; A. Oroumei; S. Dadvar; A. Fallah-Shojaie; Gh. Khayati; O. Emamgholipur

2011-01-01

214

A simple method to synthesize triangular silver nanoparticles by light irradiation  

Microsoft Academic Search

We describe a simple method to synthesize triangular silver nanoparticles by photoreducing the silver ions by citrate. A noteworthy difference of the present method as compared with the previous photo-induced methods is that good shape control over the nanoparticles can be realized in the absence of soft templates or polymer directing agents. The formation process of the silver nanoparticles was

Huiying Jia; Weiqing Xu; Jing An; Dongmei Li; Bing Zhao

2006-01-01

215

Graphene layer number dependent size distribution of silver nanoparticles  

NASA Astrophysics Data System (ADS)

We observe that silver atoms deposited by thermal evaporation deposition onto n-layer graphene films condense upon annealing to form nanoparticles with an average diameter and density that is determined by the layer numbers of graphene films. The optical microscopy and Raman spectroscopy were utilized to identify the number of the graphene layers and the SEM (scanning electron microscopy) was used to observe the morphologies of the particles. Systematic analysis revealed that the average sizes of the nanoparticles increased with the number of graphene layers. The density of nanoparticles decreased as the number of graphene layers increased, revealing a large variation in the surface diffusion strength of nanoparticles on the different substrates. The mechanisms of formation of these layer-dependent morphologies of silver nanoparticles are related to the surface free energy and surface diffusion of the n-layer graphenes.

Lin, Hsing-Ying; Hung, Meei-Ling; Huang, Chen-Han; Chui, Hsiang-Chen; Lin, Jui-Sheng

2014-05-01

216

Green synthesis of silver nanoparticles as antibacterial agent using Rhodomyrtus tomentosa acetone extract  

NASA Astrophysics Data System (ADS)

The capability of Rhodomyrtus tomentosa acetone extract (RAE) for the production of silver nanoparticles (AgNPs) has been explored for the first time. Silver nanoparticles with a surface plasmon resonance band centered at 420-430 nm were synthesized by reacting RAE with AgNO3. Reaction time, temperature, concentration of AgNO3 and RAE could accelerate the reduction rate of Ag+ and affect AgNPs size. The nanoparticles were found to be 10-30 nm in size and spherical in shape. XRD data demonstrated crystalline nature of AgNPs dominated by (200) facets. FTIR results showed decrease in intensity of peaks at 3394, 1716 and 1618 cm-1 indicating the involvement of O-H, carbonyl group and C=C stretching with the formation of AgNPs with RAE, respectively. The C-O-C and C-N stretching suggested the presence of many phytochemicals on the surface of the nanoparticles. High negative zeta potential values confirmed the stability of AgNPs in water. In vitro antibacterial activity of AgNPs was tested against Staphylococcus aureus using broth microdilution method. AgNPs capped with RAE demonstrated profound antibacterial activity against the organisms with minimum inhibitory concentration and minimum bactericidal concentration in the range between 3.1-6.2 and 6.2-50 ?gmL-1, respectively. The synthesized nanoparticles could be applied as an effective antimicrobial agent against staphylococcal infections.

Voravuthikunchai, Supayang P.; Chorachoo, Julalak; Jaiswal, Lily; Shankar, Shiv

2013-12-01

217

‘Sticky electrodes’ for the detection of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Detection and quantification of nanoparticles in environmental systems is a task that requires reliable and affordable analytical methods. Here an approach using a cysteine-modified ‘sticky’ glassy carbon electrode is presented. The electrode is immersed in a silver nanoparticle containing electrolyte and left in this suspension without an applied potential, i.e. under open circuit condition, for a variable amount of time. The amount of silver nanoparticles immobilized on the electrode within this sticking time is then determined by oxidative stripping, yielding the anodic charge and thus the amount of Ag nanoparticles sticking to the electrode surface. When using a cysteine-modified glassy carbon electrode, significant and reproducible amounts of silver nanoparticles stick to the surface, which is not the case for unmodified glassy carbon surfaces. Additionally, proof-of-concept experiments are performed on real seawater samples. These demonstrate that also under simulated environmental conditions an increased immobilization and hence improved detection of silver nanoparticles on cysteine-modified glassy carbon electrodes is achieved, while no inhibitive interference with this complex matrix is observed.

Tschulik, Kristina; Palgrave, Robert G.; Batchelor-McAuley, Christopher; Compton, Richard G.

2013-07-01

218

Green biosynthesis of silver nanoparticles using Curcuma longa tuber powder  

PubMed Central

Green synthesis of noble metal nanoparticles is a vastly developing area of research. Metallic nanoparticles have received great attention from chemists, physicists, biologists, and engineers who wish to use them for the development of a new-generation of nanodevices. In this study, silver nanoparticles were biosynthesized from aqueous silver nitrate through a simple and eco-friendly route using Curcuma longa tuber-powder extracts, which acted as a reductant and stabilizer simultaneously. Characterizations of nanoparticles were done using different methods, which included ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray fluorescence spectrometry, and Fourier-transform infrared spectroscopy. The ultraviolet-visible spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 415 nm. Transmission electron microscopy showed that mean diameter and standard deviation for the formation of silver nanoparticles was 6.30 ± 2.64 nm. Powder X-ray diffraction showed that the particles are crystalline in nature, with a face-centered cubic structure. The most needed outcome of this work will be the development of value-added products from C. longa for biomedical and nanotechnology-based industries.

Shameli, Kamyar; Ahmad, Mansor Bin; Zamanian, Ali; Sangpour, Parvanh; Shabanzadeh, Parvaneh; Abdollahi, Yadollah; Zargar, Mohsen

2012-01-01

219

'Sticky electrodes' for the detection of silver nanoparticles.  

PubMed

Detection and quantification of nanoparticles in environmental systems is a task that requires reliable and affordable analytical methods. Here an approach using a cysteine-modified 'sticky' glassy carbon electrode is presented. The electrode is immersed in a silver nanoparticle containing electrolyte and left in this suspension without an applied potential, i.e. under open circuit condition, for a variable amount of time. The amount of silver nanoparticles immobilized on the electrode within this sticking time is then determined by oxidative stripping, yielding the anodic charge and thus the amount of Ag nanoparticles sticking to the electrode surface. When using a cysteine-modified glassy carbon electrode, significant and reproducible amounts of silver nanoparticles stick to the surface, which is not the case for unmodified glassy carbon surfaces. Additionally, proof-of-concept experiments are performed on real seawater samples. These demonstrate that also under simulated environmental conditions an increased immobilization and hence improved detection of silver nanoparticles on cysteine-modified glassy carbon electrodes is achieved, while no inhibitive interference with this complex matrix is observed. PMID:23807154

Tschulik, Kristina; Palgrave, Robert G; Batchelor-McAuley, Christopher; Compton, Richard G

2013-07-26

220

Sulfidation of Silver Nanoparticles: Natural antidote to their toxicity  

PubMed Central

Nanomaterials are highly dynamic in biological and environmental media. A critical need for advancing environmental health and safety research for nanomaterials is to identify commonly occurring physical and chemical transformations affecting nanomaterial properties and toxicity. Silver nanoparticles, one of the most ecotoxic and well-studied nanomaterials, readily sulfidize in the environment. Here, we show that very low degrees of sulfidation (0.019 S/Ag mass ratio) universally and significantly decreases the toxicity of silver nanoparticles to four diverse types of aquatic and terrestrial eukaryotic organisms. Toxicity reduction is primarily associated with a decrease in Ag+ availability after sulfidation due to the lower solubility of Ag2S relative to elemental Ag (Ag(0)). We also show that chloride in exposure media determines silver nanoparticle toxicity by controlling the speciation of Ag. These results highlight the need to consider environmental transformation of NPs in assessing their toxicity to accurately portray their potential environmental risks.

Levard, Clement; Hotze, Ernest M.; Colman, Benjamin P.; Truong, Lisa; Yang, X. Y.; Bone, Audrey; Brown, Gordon E.; Tanguay, Robert L.; Di Giulio, Richard T.; Bernhardt, Emily S.; Meyer, Joel N.; Wiesner, Mark R.; Lowry, Gregory V.

2014-01-01

221

Adsorption of cations onto the surfaces of silver nanoparticles.  

PubMed

The effects of cations on the absorption spectra of silver sols have been investigated by the UV-vis spectrometry and TEM. Experiments showed that injection of certain amounts of transition metal cations into silver sols resulted not only in the aggregation of silver nanoparticles but also in the appearance of a new band centered near 510 nm in the absorption spectra of silver sols. However, the new band was not observed in the presence of alkaline earth metal cations or the Mv2+ cations. The peak position of the new band depends on the nature as well as the concentration of metal cations used. Comparing the peak positions of the new bands, it was found that the new band induced by the injection of Cr3+ was red-shifted with respect to those induced by Cu2+, Zn2+, or the Cd2+ cations. It is reasonable that this band near 510 nm should be attributed to the coeffects of the adsorption of metal cations onto the surfaces of silver nanoparticles and the aggregation of silver nanoparticles. PMID:16256471

Liu, Yun; Liu, Chun-Yan; Chen, Lin-Bo; Zhang, Zhi-Ying

2003-01-15

222

The morphology of silver nanoparticles prepared by enzyme-induced reduction  

PubMed Central

Summary Silver nanoparticles were synthesized by an enzyme-induced growth process on solid substrates. In order to customize the enzymatically grown nanoparticles (EGNP) for analytical applications in biomolecular research, a detailed study was carried out concerning the time evolution of the formation of the silver nanoparticles, their morphology, and their chemical composition. Therefore, silver-nanoparticle films of different densities were investigated by using scanning as well as transmission electron microscopy to examine their structure. Cross sections of silver nanoparticles, prepared for analysis by transmission electron microscopy were additionally studied by energy-dispersive X-ray spectroscopy in order to probe their chemical composition. The surface coverage of substrates with silver nanoparticles and the maximum particle height were determined by Rutherford backscattering spectroscopy. Variations in the silver-nanoparticle films depending on the conditions during synthesis were observed. After an initial growth state the silver nanoparticles exhibit the so-called desert-rose or nanoflower-like structure. This complex nanoparticle structure is in clear contrast to the auto-catalytically grown spherical particles, which maintain their overall geometrical appearance while increasing their diameter. It is shown, that the desert-rose-like silver nanoparticles consist of single-crystalline plates of pure silver. The surface-enhanced Raman spectroscopic (SERS) activity of the EGNP structures is promising due to the exceptionally rough surface structure of the silver nanoparticles. SERS measurements of the vitamin riboflavin incubated on the silver nanoparticles are shown as an exemplary application for quantitative analysis.

Schuler, Thomas; Strelau, Katharina K; Weber, Karina; Cialla, Dana; Diegel, Marco; Mattheis, Roland; Berger, Andreas; Moller, Robert; Popp, Jurgen

2012-01-01

223

Layer-by-layer assembly of capped CdSe nanoparticles: Electrical bistability and memory phenomenon  

Microsoft Academic Search

The authors demonstrate thin-film formation of capped-CdSe nanoparticles via layer-by-layer electrostatic assembly. The assembly of two types of nanoparticles in sequence—with anionic and cationic capping agents, respectively—results in thin films of CdSe nanoparticles. Devices based on such thin films demonstrate electrical bistability. The bistability, which is reversible in nature, is due to charge confinement in the nanoparticles and has an

Satyajit Sahu; Swarup K. Majee; Amlan J. Pal

2007-01-01

224

Layer-by-layer assembly of capped CdSe nanoparticles: Electrical bistability and memory phenomenon  

Microsoft Academic Search

The authors demonstrate thin-film formation of capped-CdSe nanoparticles via layer-by-layer electrostatic assembly. The assembly of two types of nanoparticles in sequence-with anionic and cationic capping agents, respectively-results in thin films of CdSe nanoparticles. Devices based on such thin films demonstrate electrical bistability. The bistability, which is reversible in nature, is due to charge confinement in the nanoparticles and has an

Satyajit Sahu; Swarup K. Majee; Amlan J. Pal

2007-01-01

225

Silver Nanoparticles as Real Topical Bullets for Wound Healing  

PubMed Central

Nanotechnology is on the threshold of providing a host of new materials and approaches, revolutionizing the medical and pharmaceutical fields. Several areas of medical care are already profiting from the advantage that nanotechnology offers. Recently, silver nanoparticles are attracting interest for a clinical application because of its potential biological properties such as antibacterial activity, anti-inflammatory effects, and wound healing efficacy, which could be exploited in developing better dressings for wounds and ulcers. This article reviews the role of silver nanoparticles in wound healing.

Gunasekaran, Thirumurugan; Nigusse, Tadele; Dhanaraju, Magharla Dasaratha

2012-01-01

226

Synthesis of silver nanoparticles from Melia dubia leaf extract and their in vitro anticancer activity  

NASA Astrophysics Data System (ADS)

Silver nanoparticles have a significant role in the pharmaceutical science. Especially, silver nanoparticles synthesized by the plant extracts lead a significant role in biological activities such as antimicrobial, antioxidant and anticancer. Keeping this in mind, the present work investigation has been taken up with the synthesized silver nanoparticles using the plant extract of Melia dubia and it characterizes by using UV-visible, XRD and SEM-EDS. The effect of the silver nanoparticles on human breast cancer (KB) cell line has been tested. Silver nanoparticles showed remarkable cytotoxicity activity against KB cell line with evidence of high therapeutic index value are the results are discussed.

Kathiravan, V.; Ravi, S.; Ashokkumar, S.

2014-09-01

227

Synthesis of silver nanoparticles from Melia dubia leaf extract and their in vitro anticancer activity.  

PubMed

Silver nanoparticles have a significant role in the pharmaceutical science. Especially, silver nanoparticles synthesized by the plant extracts lead a significant role in biological activities such as antimicrobial, antioxidant and anticancer. Keeping this in mind, the present work investigation has been taken up with the synthesized silver nanoparticles using the plant extract of Melia dubia and it characterizes by using UV-visible, XRD and SEM-EDS. The effect of the silver nanoparticles on human breast cancer (KB) cell line has been tested. Silver nanoparticles showed remarkable cytotoxicity activity against KB cell line with evidence of high therapeutic index value are the results are discussed. PMID:24769382

Kathiravan, V; Ravi, S; Ashokkumar, S

2014-09-15

228

Comparison of the toxicity of silver, gold and platinum nanoparticles in developing zebrafish embryos.  

PubMed

Nanoparticles have diverse applications in electronics, medical devices, therapeutic agents and cosmetics. While the commercialization of nanoparticles is rapidly expanding, their health and environmental impact is not well understood. Toxicity assays of silver, gold, and platinum nanoparticles, using zebrafish embryos to study their developmental effects were carried out. Gold (Au-NP, 15-35 nm), silver (Ag-NP, 5-35 nm) and platinum nanoparticles (Pt-NP, 3-10 nm) were synthesized using polyvinyl alcohol (PVA) as a capping agent. Toxicity was recorded in terms of mortality, hatching delay, phenotypic defects and metal accumulation. The addition of Ag-NP resulted in a concentration-dependant increase in mortality rate. Both Ag-NP and Pt-NP induced hatching delays, as well as a concentration dependant drop in heart rate, touch response and axis curvatures. Ag-NP also induced other significant phenotypic changes including pericardial effusion, abnormal cardiac morphology, circulatory defects and absence or malformation of the eyes. In contrast, Au-NP did not show any indication of toxicity. Uptake and accumulation of nanoparticles in embryos was confirmed by inductively coupled plasma optical emission spectroscopy (ICP-OES), which revealed detectable levels in embryos within 72 hpf. Ag-NP and Au-NP were taken up by the embryos in relatively equal amounts whereas lower Pt concentrations were observed in embryos exposed to Pt-NP. This was probably due to the small size of the Pt nanoparticles compared to Ag-NP and Au-NP, thus resulting in fewer metal atoms being retained in the embryos. Among the nanoparticles studied, Ag-NPs were found to be the most toxic and Au-NPs the non-toxic. The toxic effects exhibited by the zebrafish embryos as a consequence of nanoparticle exposure, accompanied by the accumulation of metals inside the body calls for urgent further investigations in this field. PMID:21417687

Asharani, P V; Lianwu, Yi; Gong, Zhiyuan; Valiyaveettil, Suresh

2011-03-01

229

Deposition of silver nanoparticles on titanium surface for antibacterial effect  

PubMed Central

Microbial colonization on implanted devices and biofilm formation is a recurrent complication in implant surgery and may result in loss of implants. The aim of this study was to deposit silver nanoparticles on a titanium surface to obtain antibacterial properties. In the present study, we prepared a silver nanoparticle-modified titanium (Ti-nAg) surface using silanization method. The morphology and chemical components of the Ti-nAg surface were characterized by scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS). Two species of bacteria, Staphylococcus aureus and Escherichia coli, were utilized to test the antibacterial effect of the Ti-nAg treated surface. The SEM examination revealed that a small quantity of silver nanoparticles was sparsely deposited on the titanium surface. The diameter of these nanoparticles ranged from ten to several hundred nm. EDS analyses revealed that there was 4.26% of Ag present on the surface. After a 24-hour incubation, 94% of Staphylococcus aureus and over 95% of Escherichia coli had been killed on the Ti-nAg surface, and the SEM examination of anti-adhesive efficacy test showed that there were less bacteria attached to Ti-nAg surface than to a control surface of untreated Titanium. These data suggest that silver nanoparticle-modified titanium is a promising material with an antibacterial property that may be used as an implantable biomaterial.

Juan, Liao; Zhimin, Zhu; Anchun, Mo; Lei, Li; Jingchao, Zhang

2010-01-01

230

Core shell silver/silver chloride nanoparticles on carbon nanofibre arrays for bio-potential monitoring  

NASA Astrophysics Data System (ADS)

We report a novel electrode material for the detection of human bio-potentials using carbon nanofibre (CNF) arrays functionalized with silver/silver chloride (Ag-AgCl) core-shell nanoparticles. The CNFs are protected against detachment using a thin polymer film, which firmly secures the fibres to the substrate surface. The core-shell Ag-AgCl nanoparticles on the CNF surfaces clearly enhance transduction in ionic media as shown by cyclic voltammetry and impedance spectroscopy. We infer that these functionalized CNF arrays can be utilized as dry electrophysiological sensors for bio-potential monitoring applications.

Watts, Paul C. P.; Henley, Simon J.; Mendoza, Ernest; Silva, S. Ravi P.; Irvine, June K.; McAdams, Eric T.

2007-05-01

231

Development of nanostructured silver vanadates decorated with silver nanoparticles as a novel antibacterial agent.  

PubMed

In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin. PMID:20378952

Holtz, R D; Souza Filho, A G; Brocchi, M; Martins, D; Durán, N; Alves, O L

2010-05-01

232

Modeling molecular effects on plasmon transport: silver nanoparticles with tartrazine.  

PubMed

Modulation of plasmon transport between silver nanoparticles by a yellow fluorophore, tartrazine, is studied theoretically. The system is studied by combining a finite-difference time-domain Maxwell treatment of the electric field and the plasmons with a time-dependent parameterized method number 3 simulation of the tartrazine, resulting in an effective Maxwell?Schro?dinger (i.e., classical?quantum) method. The modeled system has three linearly arranged small silver nanoparticles with a radius of 2 nm and a center-to-center separation of 4 nm; the molecule is centered between the second and third nanoparticles. We initiate an x-polarized current on the first nanoparticle and monitor the transmission through the system. The molecule rotates much of the x-polarized current into the y-direction and greatly reduces the overall transmission of x-polarized current. PMID:21361521

Arntsen, Christopher; Lopata, Kenneth; Wall, Michael R; Bartell, Lizette; Neuhauser, Daniel

2011-02-28

233

Synthesis and spectroscopic studies of stable aqueous dispersion of silver nanoparticles  

NASA Astrophysics Data System (ADS)

A facile approach for the synthesis of stable aqueous dispersion of silver nanoparticles (AgNPs) using glucose as the reducing agent in water/micelles system, in which cetyltrimethylammonium bromide (CTAB) was used as capping agent (stabilizer) is described. The evolution of plasmon band of AgNPs was monitored under different conditions such as (a) concentration of sodium hydroxide, (b) concentration of glucose, (c) concentration of silver nitrate (d) concentration of CTAB, and (e) reaction time. AgNPs were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), fluorescence spectroscopy and FT-IR spectroscopy. The results revealed an easy and viable strategy for obtaining stable aqueous dispersion of AgNPs with well controlled shape and size below 30 nm in diameter.

El-Shishtawy, Reda M.; Asiri, Abdullah M.; Al-Otaibi, Maha M.

2011-09-01

234

Colloidal stability of silver nanoparticles in biologically relevant conditions  

Microsoft Academic Search

Understanding the colloidal stability of nanoparticles (NPs) plays a key role in phenomenological interpretation of toxicological\\u000a experiments, particularly if single NPs or their aggregates or agglomerates determine the dominant experimental result. This\\u000a report examines a variety of instrumental techniques for surveying the colloidal stability of aqueous suspensions of silver\\u000a nanoparticles (AgNPs), including atomic force microscopy, dynamic light scattering, and colorimetry.

Robert I. MacCuspie

2011-01-01

235

Antibacterial nano-structured titania coating incorporated with silver nanoparticles  

Microsoft Academic Search

Titanium (Ti) implants are widely used clinically but post-operation infection remains one of the most common and serious complications. A surface boasting long-term antibacterial ability is highly desirable in order to prevent implant associated infection. In this study, titania nanotubes (TiO2-NTs) incorporated with silver (Ag) nanoparticles are fabricated on Ti implants to achieve this purpose. The Ag nanoparticles adhere tightly

Lingzhou Zhao; Hairong Wang; Kaifu Huo; Lingyun Cui; Wenrui Zhang; Hongwei Ni; Yumei Zhang; Zhifen Wu; Paul K. Chu

2011-01-01

236

Synthesis and Characterization of Silver Nanoparticles Embedded in Emulsified Isobutyl Acrylate  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were generated using laser ablation technique in emulsified isobutyl acrylate solution in which the nanoparticles are stabilized and embedded over the acrylic polymerized solution. Further, the colloidal solutions were characterized with atomic force microscope (AFM), scanning electron microscope (SEM) and Fourier transform infrared spectrophotometer (FTIR). AFM image results of the nanoparticles displays the silver nanoparticles embedded over the emulsified acrylic layer and dispersion of spherical nanoparticles across the polymer were eruptions of silver nanoparticles can be seen clearly. In addition, FTIR spectrum and SEM images validate the nanoparticle reaction over the polymerized acrylate solution and size of the metal nanoparticles respectively.

Dennis, C.; Vidhya, S.; Shadak Alee, K.; Narayana Rao, D.

2013-01-01

237

Exposure to silver nanoparticles induces oxidative stress and memory deficits in laboratory rats  

Microsoft Academic Search

Currently most of the applications of silver nanoparticles are in antibacterial\\/antifungal agents in medicine and biotechnology,\\u000a textile engineering, water treatment and silver-based consumer products. However, the effects of silver nanoparticles on human\\u000a body, especially on the central nervous system, are still unclear. To study the mechanisms underlying the effects of silverpoly(amidehydroxyurethane)\\u000a coated silver nanoparticles on brain functions, we subjected male

Lucian Hritcu; Marius Stefan; Laura Ursu; Anca Neagu; Marius Mihasan; Liliana Tartau; Viorel Melnig

2011-01-01

238

Dermal exposure potential from textiles that contain silver nanoparticles.  

PubMed

Background: Factors that influence exposure to silver particles from the use of textiles are not well understood. Objectives: The aim of this study was to evaluate the influence of product treatment and physiological factors on silver release from two textiles. Methods: Atomic and absorbance spectroscopy, electron microscopy, and dynamic light scattering (DLS) were applied to characterize the chemical and physical properties of the textiles and evaluate silver release in artificial sweat and saliva under varying physiological conditions. One textile had silver incorporated into fiber threads (masterbatch process) and the other had silver nanoparticles coated on fiber surfaces (finishing process). Results: Several complementary and confirmatory analytical techniques (spectroscopy, microscopy, etc.) were required to properly assess silver release. Silver released into artificial sweat or saliva was primarily in ionic form. In a simulated "use" and laundering experiment, the total cumulative amount of silver ion released was greater for the finishing process textile (0·51±0·04%) than the masterbatch process textile (0·21±0·01%); P<0·01. Conclusions: We found that the process (masterbatch vs finishing) used to treat textile fibers was a more influential exposure factor than physiological properties of artificial sweat or saliva. PMID:25000110

Stefaniak, Aleksandr B; Duling, Mathew G; Lawrence, Robert B; Thomas, Treye A; LeBouf, Ryan F; Wade, Eleanor E; Abbas Virji, M

2014-07-01

239

Biosynthesis of silver nanoparticles using Plectranthus amboinicus leaf extract and its antimicrobial activity  

NASA Astrophysics Data System (ADS)

This study reports the simple green synthesis method for the preparation of silver nanoparticles (Ag NPs) using Plectranthus amboinicus leaf extract. The pathway of nanoparticles formation is by means of reduction of AgNO3 by leaf extract, which acts as both reducing and capping agents. Synthesized Ag NPs were subjected to different characterizations for studying the structural, chemical, morphological, optical and antimicrobial properties. The bright circular fringes in SAED pattern and diffraction peaks in XRD profile reveals high crystalline nature of biosynthesized Ag NPs. Morphological studies shows the formation of nearly spherical nanoparticles. FTIR spectrum confirms the existence of various functional groups of biomolecules capping the nanoparticles. UV-visible spectrum displays single SPR band at 428 nm indicating the absence of anisotropic particles. The synthesized Ag NPs exhibited better antimicrobial property towards gram negative Escherichia coli and towards tested Penicillium spp. than other tested microorganisms using disc diffusion method. Finally it has proven that the synthesized bio-inspired Ag NPs have potent antimicrobial effect.

Ajitha, B.; Ashok Kumar Reddy, Y.; Sreedhara Reddy, P.

240

Biosynthesis of silver nanoparticles using Plectranthus amboinicus leaf extract and its antimicrobial activity.  

PubMed

This study reports the simple green synthesis method for the preparation of silver nanoparticles (Ag NPs) using Plectranthus amboinicus leaf extract. The pathway of nanoparticles formation is by means of reduction of AgNO3 by leaf extract, which acts as both reducing and capping agents. Synthesized Ag NPs were subjected to different characterizations for studying the structural, chemical, morphological, optical and antimicrobial properties. The bright circular fringes in SAED pattern and diffraction peaks in XRD profile reveals high crystalline nature of biosynthesized Ag NPs. Morphological studies shows the formation of nearly spherical nanoparticles. FTIR spectrum confirms the existence of various functional groups of biomolecules capping the nanoparticles. UV-visible spectrum displays single SPR band at 428nm indicating the absence of anisotropic particles. The synthesized Ag NPs exhibited better antimicrobial property towards gram negative Escherichia coli and towards tested Penicillium spp. than other tested microorganisms using disc diffusion method. Finally it has proven that the synthesized bio-inspired Ag NPs have potent antimicrobial effect. PMID:24674916

Ajitha, B; Ashok Kumar Reddy, Y; Sreedhara Reddy, P

2014-07-15

241

Silver nanoparticle enhanced silver ion stress response in Escherichia coli K12.  

PubMed

This study investigated the dissolution-based toxicity mechanism for silver nanoparticles to Escherichia coli K12. The silver nanoparticles, synthesised in the vapour phase, are effective anti-bacterial agents against the Gram-negative bacterium, E. coli K12. The nanoparticles associate with the bacterial cell wall, appearing to interact with the outer and inner membranes, and then dissolve to release Ag(+) into the cell and affect a transcriptional response. The dissolution of these nanoparticles in a modified LB medium was measured by inductively coupled plasma mass spectrometry (ICP-MS) and has been shown to follow a simple first-order dissolution process proportional to the decreasing surface area of the nanoparticles. However, the resulting solution phase concentration of Ag(+), demonstrated by the ICP-MS data, is not sufficient to cause the observed effects, including inhibition of bacterial growth and the differential expression of Cu(+) stress response genes. These data indicate that dissolution at the cell membrane is the primary mechanism of action of silver nanoparticles, and the Ag(+) concentration released into the bulk solution phase has only limited anti-bacterial efficacy. PMID:22007647

McQuillan, Jonathan S; Infante, Heidi Groenaga; Stokes, Emma; Shaw, Andrew M

2012-12-01

242

Self-assembly of TOPO-derivatized silver nanoparticles into multilayered film.  

SciTech Connect

A novel method for transferring silver nanoparticles from aqueous solution into organic solvents such as toluene or hexane was developed. Phase-transfer reagent, tri-n-octylphosphine oxide, TOPO, provides a capping shell around Ag particles that enables concentrating nanoparticle dispersion in toluene, which is a prerequisite for successful 3D self-assembly. The dispersed particles are stable for a long period of time (at least six months). Self-assembly of high concentrations of TOPO-capped Ag particles results in a multilayered mirrorlike film formed onto glass substrates. SEM images reveal a fine-grained film consisting of 10-nm close-packed particles. The surface plasmon absorption of the 3D structure is 100 nm red-shifted compared to that of isolated particles in toluene solution, and is a result of interparticle coupling of dielectric functions of particles in near proximity. Redispersing of particles from the 3D film into toluene solution revealed a spectrum of silver particles virtually identical to that of the original solution used for the formation of the multilayered film. This confirms that the shift of surface plasmon absorption of 3D film is a result of interparticle communication/coupling.

Saponjic, Z. V.; Csencsits, R.; Rajh, T.; Dimitrijevic, N. M.

2003-11-18

243

Synthesis and properties of silver nanoparticles: advances and prospects  

NASA Astrophysics Data System (ADS)

Conventional and novel syntheses of silver nanoparticles are considered, their advantages and shortcomings are analysed. Attention is focused on the shape-controlled methods of preparation of nanosized particles. The unique optical and antibacterial properties of nanosilver and related applications are discussed.

Krutyakov, Yu A.; Kudrinskiy, A. A.; Olenin, A. Yu; Lisichkin, G. V.

2008-03-01

244

Antimicrobial Properties of Hydrated Cellulose Membranes With Silver Nanoparticles  

Microsoft Academic Search

Microbial cellulose membranes have attracted a great deal of attention as novel wound-dressing materials, especially for the healing of skin burns and chronic wounds, because of their high water holding capacity and biocompatibility. However, the high humidity around the wound sometimes allows the growth of bacteria, as well as the regeneration of the tissue. In this study, silver nanoparticles were

Rira Jung; Yeseul Kim; Hun-Sik Kim; Hyoung-Joon Jin

2009-01-01

245

Silver nanoparticles are broad-spectrum bactericidal and virucidal compounds  

PubMed Central

The advance in nanotechnology has enabled us to utilize particles in the size of the nanoscale. This has created new therapeutic horizons, and in the case of silver, the currently available data only reveals the surface of the potential benefits and the wide range of applications. Interactions between viral biomolecules and silver nanoparticles suggest that the use of nanosystems may contribute importantly for the enhancement of current prevention of infection and antiviral therapies. Recently, it has been suggested that silver nanoparticles (AgNPs) bind with external membrane of lipid enveloped virus to prevent the infection. Nevertheless, the interaction of AgNPs with viruses is a largely unexplored field. AgNPs has been studied particularly on HIV where it was demonstrated the mechanism of antiviral action of the nanoparticles as well as the inhibition the transmission of HIV-1 infection in human cervix organ culture. This review discusses recent advances in the understanding of the biocidal mechanisms of action of silver Nanoparticles.

2011-01-01

246

Silver nanoparticles: synthesis and size control by electron irradiation  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were synthesized by irradiating solutions, prepared by mixing AgNO3 and poly-vinyl alcohol (PVA), with 6 MeV electrons. The electron-irradiated solutions and the thin coatings cast from them were characterized using the ultraviolet-visible (UV-vis), x-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. During electron irradiation, the process of formation of the silver nanoparticles appeared to be initiated at an electron fluence of ~2 × 1013 e cm-2. This was evidenced from the solution, which turned yellow and exhibited the characteristic plasmon absorption peak around 455 nm. Silver nanoparticles of different sizes in the range 60-10 nm, with a narrow size distribution, could be synthesized by varying the electron fluence from 2 × 1013 to 3 × 1015 e cm-2. Silver nanoparticles of sizes in the range 100-200 nm were also synthesized by irradiating an aqueous AgNO3 solution with 6 MeV electrons.

Bogle, K. A.; Dhole, S. D.; Bhoraskar, V. N.

2006-07-01

247

Synthesis and properties of silver nanoparticles: advances and prospects  

Microsoft Academic Search

Conventional and novel syntheses of silver nanoparticles are considered, their advantages and shortcomings are analysed. Attention is focused on the shape-controlled methods of preparation of nanosized particles. The unique optical and antibacterial properties of nanosilver and related applications are discussed.

Yu A. Krutyakov; A. A. Kudrinskiy; A. Yu Olenin; G. V. Lisichkin

2008-01-01

248

Silver nanoparticles: Large scale solvothermal synthesis and optical properties  

SciTech Connect

Silver nanoparticles have been successfully synthesized by a simple and modified solvothermal method at large scale using ethanol as the refluxing solvent and NaBH{sub 4} as reducing agent. The nanopowder was investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-visible and BET surface area studies. XRD studies reveal the monophasic nature of these highly crystalline silver nanoparticles. Transmission electron microscopic studies show the monodisperse and highly uniform nanoparticles of silver of the particle size of 5 nm, however, the size is found to be 7 nm using dynamic light scattering which is in good agreement with the TEM and X-ray line broadening studies. The surface area was found to be 34.5 m{sup 2}/g. UV-visible studies show the absorption band at {approx}425 nm due to surface plasmon resonance. The percentage yield of silver nanoparticles was found to be as high as 98.5%.

Wani, Irshad A.; Khatoon, Sarvari [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)] [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India) [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Ahmed, Jahangeer; Ganguli, Ashok K. [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India)] [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Ahmad, Tokeer, E-mail: tokeer.ch@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)] [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)

2010-08-15

249

Interaction of multi-functional silver nanoparticles with living cells  

Microsoft Academic Search

Silver nanoparticles (AgNPs) are widely used in household products and in medicine due to their antibacterial and to wound healing properties. In recent years, there is also an effort for their use in biomedical imaging and photothermal therapy. The primary reason behind the effort for their utility in biomedicine and therapy is their unique plasmonic properties and easy surface chemistry

Ilknur Sur; Dilek Cam; Mehmet Kahraman; Asli Baysal; Mustafa Culha

2010-01-01

250

Ecosystem protection by effluent bioremediation: silver nanoparticles impregnation in a textile fabrics process  

Microsoft Academic Search

This work studied a bioremediation process of silver nanoparticles with the bacterium Chromobacterium violaceum. These nanoparticles were obtained from several washes of cotton fabrics impregnated with silver nanoparticles produced by\\u000a the fungus Fusarium oxysporum. The optimized growth of C. violaceum for silver nanoparticles bioremediation was obtained. The effluents of wash process of the cotton fabric were efficiently\\u000a treated with C.

Nelson Durán; Priscyla D. Marcato; Oswaldo L. Alves; João P. S. Da Silva; Gabriel I. H. De Souza; Flávio A. Rodrigues; Elisa Esposito

2010-01-01

251

In Vivo Toxicity of Silver Nanoparticles and Silver Ions in Zebrafish (Danio rerio).  

PubMed

The influence of water chemistry on characterised polyvinyl pyrrolidone- (PVP-) coated silver nanoparticles (81?nm) was investigated. NaCl solution series of 100-800?mg L(-1) lead to initial and temporal increase in nanoparticles size, but agglomeration was limited. pH variation (5-8) had only minor influence on the hydrodynamic particle size. Acute toxicity of nanosivler to zebrafish (Danio rerio) was investigated in a 48-hour static renewal study and compared with the toxicity of silver ions (AgNO(3)). The nanosilver and silver ion 48-hour median lethal concentration (LC(50)) values were 84??g L(-1) and 25??g L(-1), respectively. To investigate exposure-related stress, the fish behaviour was observed visually after 0, 3, 6, 12, 24, 27, 30, and 48 hours of both nanosilver and ionic silver treatments. These observations revealed increased rate of operculum movement and surface respiration after nanosilver exposure, suggesting respiratory toxicity. The present study demonstrates that silver nanoparticles are lethal to zebrafish. PMID:22174711

Bilberg, Katrine; Hovgaard, Mads Bruun; Besenbacher, Flemming; Baatrup, Erik

2012-01-01

252

PEG conjugated citrate-capped magnetite nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

We aim to develop polyethylene glycol decorated, citric acid capped magnetite nanoparticles (MNPs) with proper physicochemical characteristics including particle size distribution, morphology, magnetic property and stability in a biologic medium. MNP of about 10 nm were synthesized by a biocompatible chemical co-precipitation of Fe2+ and Fe3+ in an ammonia solution. A synthetic methodology has been developed to get a well dispersed and homogeneous aqueous suspension of MNPs. The naked MNPs are often insufficient for their stability, hydrophilicity and further functionalization. In order to overcome these limitations, citric acid was used to stabilize the magnetite particle suspension, which was anchored on the surface of freshly prepared MNPs by a direct addition method. Polyethylene glycol was covalently attached to the carboxylic moieties of citric acid anchored MNPs by carbodiimide chemistry. The microstructure and morphology of the nanoparticles were characterized by X-ray diffraction and transmission electron microscopy, and Fourier transform infrared spectroscopy. Also, the magnetic properties were investigated by vibrating sample magnetometry. It was found that the nanoparticles demonstrated superparamagnetic behavior.

Cheraghipour, Elham; Tamaddon, A. M.; Javadpour, S.; Bruce, I. J.

2013-02-01

253

Green synthesis of xanthan conformation-based silver nanoparticles: antibacterial and catalytic application.  

PubMed

Silver nanoparticles (Ag NPs) were green synthetized using xanthan gum (XG) dissolved in water as reducing and capping agent for the first time. The structure, morphology, and size of Ag NPs in XG aqueous solutions were investigated with UV-vis spectroscopy, transmission electron microscopy and Fourier transform infrared. The results indicated Ag NPs were integrated successfully in the XG matrix and the optical properties and morphology of Ag NPs could be regulated by the synthesis condition. The aggregation of the XG-bonded Ag NPs increased with storage, whereas the size barely changed. The assemble behavior was related to the XG conformation transition of denaturation and renaturation. The one spot formed Ag NPs showed favorable antibacterial effect on Escherichia coli and Staphyloccocus aureus and excellent catalytic capability of 4-nitrophenol reduction. This work provided a feasible method to detect the biopolymer space structure transition through the intensity of metal nanoparticles labeled on the chain. PMID:24299862

Xu, Wei; Jin, Weiping; Lin, Liufeng; Zhang, Chunlan; Li, Zhenshun; Li, Yan; Song, Rong; Li, Bin

2014-01-30

254

Development of antimicrobial water filtration hybrid material from bio source calcium carbonate and silver nanoparticles  

NASA Astrophysics Data System (ADS)

Biobased calcium carbonate and silver hybrid nanoparticles were synthesized using a simple mechanochemical milling technique. The XRD spectrum showed that the hybrid materials is composed of crystalline calcite and silver nanoparticles. The TEM results indicated that the silver nanoparticles are discrete, uncapped and well stabilized in the surface of the eggshell derived calcium carbonate particles. The silver nanoparticles are spherical in shape and 5-20 nm in size. The SEM studies indicated that the eggshells are in micron size with the silver nanoparticle embedded in their surface. The hybrid eggshell/silver nanocomposite exhibited superior inhibition of E. coli growth using the Kirby-Bauer discs diffusion assay and comparing the zone of inhibition around the filter paper disc impregnated with the hybrid particles against pristine silver nanoparticles.

Apalangya, Vitus; Rangari, Vijaya; Tiimob, Boniface; Jeelani, Shaik; Samuel, Temesgen

2014-03-01

255

Assessment of silver nanoparticle-induced physiological and molecular changes in Arabidopsis thaliana.  

PubMed

In this study, the effect of silver nanoparticles and silver ions on Arabidopsis thaliana was investigated at physiological and molecular levels. The seedlings were grown in sublethal concentrations of silver nanoparticles and silver ions (0.2, 0.5, and 1 mg/L) in 1/4 Hoagland's medium for 14 days under submerged hydroponic conditions. Significantly higher reduction in the total chlorophyll and increase in anthocyanin content were observed after exposure to 0.5 and 1 mg/L silver nanoparticles as compared to similar concentrations of silver ions. Lipid peroxidation increased significantly after exposure to 0.2, 0.5, and 1 mg/L of silver nanoparticles and 0.5 and 1 mg/L of silver ions. Qualitative analysis with dichloro-dihydro-fluorescein diacetate and rhodamine 123 fluorescence showed a dose-dependent increase in reactive oxygen species production and changes in mitochondrial membrane potential in the roots of seedlings exposed to different concentrations of silver nanoparticles. Real-time PCR analysis showed significant upregulation in the expression of sulfur assimilation, glutathione biosynthesis, glutathione S-transferase, and glutathione reductase genes upon exposure to silver nanoparticles as compared with silver ions. Overall, based on the physiological and molecular level responses, it was observed that exposure to silver nanoparticles exerted more toxic response than silver ions in A. thaliana. PMID:24723349

Nair, Prakash M Gopalakrishnan; Chung, Ill Min

2014-07-01

256

Determination of silver nanoparticle release from antibacterial fabrics into artificial sweat  

Microsoft Academic Search

Silver nanoparticles have been used in numerous commercial products, including textiles, to prevent bacterial growth. Meanwhile, there is increasing concern that exposure to these nanoparticles may cause potential adverse effects on humans as well as the environment. This study determined the quantity of silver released from commercially claimed nanosilver and laboratory-prepared silver coated fabrics into various formulations of artificial sweat,

Kornphimol Kulthong; Sujittra Srisung; Kanittha Boonpavanitchakul; Wiyong Kangwansupamonkon; Rawiwan Maniratanachote

2010-01-01

257

Immobilization of silver nanoparticles onto sulfonated polyethersulfone membranes as antibacterial materials  

Microsoft Academic Search

By using the interaction between the sulfonated groups and silver ions, silver nanoparticles were successfully introduced onto the surface of sulfonated polyethersulfone (SPES) membranes by using vitamin C as reducing agent. The presence of silver nanoparticles on the surface of the PES\\/SPES hybrid membranes was characterized by UV spectrophotometer, scanning electron microscopy and transmission electron microscopy. Detailed studies on the

Xuelian Cao; Ming Tang; Fei Liu; Yuanyang Nie; Changsheng Zhao

2010-01-01

258

The production of graphene nanosheets decorated with silver nanoparticles for use in transparent, conductive films  

Microsoft Academic Search

Aggregation and restacking of graphene nanosheets (GNS) can be efficiently inhibited by decorating the silver nanoparticles on the surface of GNS to form GNS\\/silver (GNS-Ag) composites, which can construct high transparent and electrically conductive thin films. Silver nanoparticles act as a useful nanospacer and conductor, which not only increase the interlayer distance but also improve the electrical conductivity between layers.

Hsi-Wen Tien; Yuan-Li Huang; Shin-Yi Yang; Jen-Yu Wang; Chen-Chi M. Ma

2011-01-01

259

Interaction of silver nanoparticles with serum proteins affects their antimicrobial activity in vivo.  

PubMed

The emergence of multidrug-resistant bacteria is a global threat for human society. There exist recorded data that silver was used as an antimicrobial agent by the ancient Greeks and Romans during the 8th century. Silver nanoparticles (AgNPs) are of potential interest because of their effective antibacterial and antiviral activities, with minimal cytotoxic effects on the cells. However, very few reports have shown the usage of AgNPs for antibacterial therapy in vivo. In this study, we deciphered the importance of the chosen methods for synthesis and capping of AgNPs for their improved activity in vivo. The interaction of AgNPs with serum albumin has a significant effect on their antibacterial activity. It was observed that uncapped AgNPs exhibited no antibacterial activity in the presence of serum proteins, due to the interaction with bovine serum albumin (BSA), which was confirmed by UV-Vis spectroscopy. However, capped AgNPs [with citrate or poly(vinylpyrrolidone)] exhibited antibacterial properties due to minimized interactions with serum proteins. The damage in the bacterial membrane was assessed by flow cytometry, which also showed that only capped AgNPs exhibited antibacterial properties, even in the presence of BSA. In order to understand the in vivo relevance of the antibacterial activities of different AgNPs, a murine salmonellosis model was used. It was conclusively proved that AgNPs capped with citrate or PVP exhibited significant antibacterial activities in vivo against Salmonella infection compared to uncapped AgNPs. These results clearly demonstrate the importance of capping agents and the synthesis method for AgNPs in their use as antimicrobial agents for therapeutic purposes. PMID:23877702

Gnanadhas, Divya Prakash; Ben Thomas, Midhun; Thomas, Rony; Raichur, Ashok M; Chakravortty, Dipshikha

2013-10-01

260

Interaction of Silver Nanoparticles with Serum Proteins Affects Their Antimicrobial Activity In Vivo  

PubMed Central

The emergence of multidrug-resistant bacteria is a global threat for human society. There exist recorded data that silver was used as an antimicrobial agent by the ancient Greeks and Romans during the 8th century. Silver nanoparticles (AgNPs) are of potential interest because of their effective antibacterial and antiviral activities, with minimal cytotoxic effects on the cells. However, very few reports have shown the usage of AgNPs for antibacterial therapy in vivo. In this study, we deciphered the importance of the chosen methods for synthesis and capping of AgNPs for their improved activity in vivo. The interaction of AgNPs with serum albumin has a significant effect on their antibacterial activity. It was observed that uncapped AgNPs exhibited no antibacterial activity in the presence of serum proteins, due to the interaction with bovine serum albumin (BSA), which was confirmed by UV-Vis spectroscopy. However, capped AgNPs [with citrate or poly(vinylpyrrolidone)] exhibited antibacterial properties due to minimized interactions with serum proteins. The damage in the bacterial membrane was assessed by flow cytometry, which also showed that only capped AgNPs exhibited antibacterial properties, even in the presence of BSA. In order to understand the in vivo relevance of the antibacterial activities of different AgNPs, a murine salmonellosis model was used. It was conclusively proved that AgNPs capped with citrate or PVP exhibited significant antibacterial activities in vivo against Salmonella infection compared to uncapped AgNPs. These results clearly demonstrate the importance of capping agents and the synthesis method for AgNPs in their use as antimicrobial agents for therapeutic purposes.

Gnanadhas, Divya Prakash; Ben Thomas, Midhun; Thomas, Rony; Raichur, Ashok M.

2013-01-01

261

Bacterial growth on a superhydrophobic surface containing silver nanoparticles  

NASA Astrophysics Data System (ADS)

The antibacterial effect of silver can be exploited in the food and beverage industry and medicinal applications to reduce biofouling of surfaces. Very small amount of silver ions are enough to destructively affect the metabolism of bacteria. Moreover, superhydrophobic properties could reduce bacterial adhesion to the surface. In this study we fabricated superhydrophobic surfaces that contained nanosized silver particles. The superhydrophobic surfaces were manufactured onto stainless steel as combination of ceramic nanotopography and hydrophobication by fluorosilane. Silver nanoparticles were precipitated onto the surface by a chemical method. The dissolution of silver from the surface was tested in an aqueous environment under pH values of 1, 3, 5, 7, 9, 11 and 13. The pH value was adjusted with nitric acid and ammonia. It was found that dissolution rate of silver increased as the pH of the solution altered from the pH of de-ionized water to lower and higher pH values but dissolution occurred also in de-ionized water. The antimicrobial potential of this coating was investigated using bacterial strains isolated from the brewery equipment surfaces. The results showed that the number of bacteria adhering onto steel surface was significantly reduced (88%) on the superhydrophobic silver containing coating.

Heinonen, S.; Nikkanen, J.-P.; Laakso, J.; Raulio, M.; Priha, O.; Levänen, E.

2013-12-01

262

Synthesis of silver nanoparticles and the optical properties  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (NPs) of 5-15 nm are synthesized with the reduction of silver nitrate (AgNO3) by formaldehyde (HCHO) and using polyethylenemine (PEI) as a stabilizer. Transmission electron microscopy (TEM) analysis shows the size of the Ag NPs increases with the increase of HCHO contents. The absorption and emission peaks of the original colloids are red shifted with increasing the size of Ag NPs. The absorption and emission peaks are at 344 nm, 349 nm, 357 nm, 362 nm, 364 nm and 444 nm, 458 nm, 519 nm, 534 nm, 550 nm, respectively. The fluorescence intensities of the silver colloids increase with increasing the NPs size (or the contents of HCHO). With the diluted fold increasing, the fluorescence intensity of the diluted silver colloids increases firstly then decreases. Compared with that of the original silver colloids, the emission peaks are blue shifted. For the diluted silver colloids, when the fluorescence intensity is maximum, the emission peaks are all near 444 nm. The 16-fold diluted silver colloid gets to the maximum emission intensity when the mole ratio of AgNO3 and HCHO is 1:6.

Yang, Ai-ling; Zhang, Zhen-zhen; Yang, Yun; Bao, Xi-chang; Yang, Ren-qiang

2013-01-01

263

Sensitive signal-on fluorescent sensing for copper ions based on the polyethyleneimine-capped silver nanoclusters-cysteine system.  

PubMed

In this work, we present a label-free sensor for copper ions. This sensor is composed of silver nanoclusters and cysteine. The fluorescence of the silver nanoclusters was quenched by cysteine, which was recovered in the presence of copper ions. This binding of silver nanoclusters to cysteine promoted agglomeration of silver nanoclusters to yield larger non-fluorescent silver nanoparticles. The presence of copper ions resulted in the oxidation of cysteine to form a disulfide compound, leading to recovery of fluorescence of the silver nanoclusters. The fluorescence of the silver nanoclusters in the presence of cysteine increased with increasing concentration of copper ions in the range of 10-200 nM. The detection limit of this sensor for copper ions was 2.3 nM. The silver nanoclusters-cysteine sensor provides a simple, cost-effective, and sensitive platform for the detection of copper ions. PMID:23890605

Zhang, Na; Qu, Fei; Luo, Hong Qun; Li, Nian Bing

2013-08-12

264

Antibacterial properties of novel poly(methyl methacrylate) nanofiber containing silver nanoparticles.  

PubMed

Poly(methyl methacrylate) (PMMA) nanofiber containing silver nanoparticles was synthesized by radical-mediated dispersion polymerization and applied to an antibacterial agent. UV-vis spectroscopic analysis indicated that the silver nanoparticles were continually released from the polymer nanofiber in aqueous solution. The antibacterial properties of silver/PMMA nanofiber against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria were evaluated using minimum inhibitory concentration (MIC), the modified Kirby-Bauer method, and a kinetic test. The MIC test demonstrated that the silver/PMMA nanofiber had enhanced antimicrobial efficacy compared to that of silver sulfadiazine and silver nitrate at the same silver concentration. PMID:18225933

Kong, Hyeyoung; Jang, Jyongsik

2008-03-01

265

Bioinspired synthesis of highly stabilized silver nanoparticles using Ocimum tenuiflorum leaf extract and their antibacterial activity  

NASA Astrophysics Data System (ADS)

Biosynthesis of nanoparticles is under exploration due to wide biomedical applications and research interest in nanotechnology. We herein reports bioinspired synthesis of silver nanoparticles with the aid of novel, non toxic ecofriendly biological material namely Ocimum tenuiflorum leaf extract. It acts as reducing as well as stabilizing agent. An intense surface plasmon resonance band at ˜450 nm in the UV-visible spectrum clearly reveals the formation of silver nanoparticles. The photoluminescence spectrum was recorded to study excitation and emission. TEM and PSD by dynamic light scattering studies showed that size of silver nanoparticles to be in range 25-40 nm. Face centered cubic structure of silver nanoparticles are confirmed by SAED pattern. The charge on synthesized silver nanoparticles was determined by zeta potential. The colloidal solution of silver nanoparticles were found to exhibit high antibacterial activity against three different strains of bacteria Escherichia coli (Gram negative), Corney bacterium (gram positive), Bacillus substilus (spore forming).

Patil, Rupali S.; Kokate, Mangesh R.; Kolekar, Sanjay S.

2012-06-01

266

Synthesis and NMR characterization of ligand-capped metal and metal-oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Ligand-capped metal and metal-oxide nanoparticles (NPs) have some interesting and useful physical properties that are not present in their respective bulk materials. These properties are of research interest in many applications such as catalysis, drug delivery, biological imaging, and plasmonics. In such applications, it is critical to understand the surface structure of NPs and the roles played by the surface bound ligands. To characterize surface environment, ligand dynamics, and exchange kinetics, ligand-capped metal and metal-oxide NPs are synthesized and studied by multinuclear NMR. Phosphines and phosphonic acids are used to passivate metal (gold and silver) and metal-oxide (tin dioxide) NPs in different sizes (1-5 nm) by following published procedures or original synthesis methods. In both solution and solid state NMR, the 31P chemical shift of surface-bound ligands are distinctly different from those observed for free ligands. Additionally, NMR line widths in surface-bound ligands are highly broadened compared to those of free ligands. The lines are broadened due to both homogeneous and inhomogeneous broadening mechanisms, determined through hole burning NMR and spin-spin relaxation measurements. In small particles (< 2 nm), the main source of line broadening is inhomogeneous and originates due to structural heterogeneity and underlying chemical shift distributions. In large particles (> 2 nm), both inhomogeneous and homogeneous line broadening mechanisms are present. When the particles' sizes increase from small to large, the homogeneous broadening mechanism becomes dominant due to strong nuclear-electron interaction and reintroduction of residual dipolar coupling as shown by a combination of 1H, 13C and 31P NMR. Results from a series of ligand exchange experiments in silver and gold NPs further indicate the presence of Au(I) and Ag(I) on the particle surfaces.

Sharma, Ramesh

267

A physiologically based pharmacokinetic model for ionic silver and silver nanoparticles  

PubMed Central

Silver is a strong antibiotic that is increasingly incorporated into consumer products as a bulk, salt, or nanosilver, thus potentially causing side-effects related to human exposure. However, the fate and behavior of (nano)silver in the human body is presently not well understood. In order to aggregate the existing experimental information, a physiologically based pharmacokinetic model (PBPK) was developed in this study for ionic silver and nanosilver. The structure of the model was established on the basis of toxicokinetic data from intravenous studies. The number of calibrated parameters was minimized in order to enhance the predictive capability of the model. We validated the model structure for both silver forms by reproducing exposure conditions (dermal, oral, and inhalation) of in vivo experiments and comparing simulated and experimentally assessed organ concentrations. Therefore, the percutaneous, intestinal, or pulmonary absorption fraction was estimated based on the blood silver concentration of the respective experimental data set. In all of the cases examined, the model could successfully predict the biodistribution of ionic silver and 15–150 nm silver nanoparticles, which were not coated with substances designed to prolong the circulatory time (eg, polyethylene glycol). Furthermore, the results of our model indicate that: (1) within the application domain of our model, the particle size and coating had a minor influence on the biodistribution; (2) in vivo, it is more likely that silver nanoparticles are directly stored as insoluble salt particles than dissolve into Ag+; and (3) compartments of the mononuclear phagocytic system play a minor role in exposure levels that are relevant for human consumers. We also give an example of how the model can be used in exposure and risk assessments based on five different exposure scenarios, namely dietary intake, use of three separate consumer products, and occupational exposure.

Bachler, Gerald; von Goetz, Natalie; Hungerbuhler, Konrad

2013-01-01

268

Presence of Nanoparticles in Wash Water from Conventional Silver and Nano-silver Textiles.  

PubMed

Questions about how to regulate nanoenhanced products regularly arise as researchers determine possible nanoparticle transformation(s). Focusing concern on the incorporation and subsequent release of nano-Ag in fabrics often overshadows the fact that many "conventional silver" antimicrobials such as ionic silver, AgCl, metallic Ag, and other forms will also form different species of silver. In this study we used a laboratory washing machine to simulate the household laundering of a number of textiles prepared with known conventional Ag or nano-Ag treatments and a commercially available fabric incorporating yarns coated with bulk metallic Ag. Serial filtration allowed for quantification of total Ag released in various size fractions (>0.45 ?m, < 0.45 ?m, <0.1 ?m, and <10 kDa), while characterization of particles with TEM/EDX provided insight on Ag transformation mechanisms. Most conventional Ag additives yielded more total Ag and more nanoparticulate-sized Ag in the washing liquid than fabrics that used nano-Ag treatments. Incorporating nano-silver into the fiber (as opposed to surface treatments) yielded less total Ag during fabric washing. A variety of metallic Ag, AgCl, and Ag/S particles were observed in washing solution by TEM/EDX to various extents depending on the initial Ag speciation in the fabrics. Very similar particles were also observed when dissolved ionic Ag was added directly into the washing liquid. On the basis of the present study, we can state that all silver-treated textiles, regardless of whether the treatment is "conventional" or "nano", can be a source of silver nanoparticles in washing solution when laundering fabrics. Indeed, in this study we observed that textiles treated with "conventional" silver have equal or greater propensity to form nano-silver particles during washing conditions than those treated with "nano"-silver. This fact needs to be strongly considered when addressing the risks of nano-silver and emphasizes that regulatory assessment of nano-silver warrants a similar approach to conventional silver. PMID:24941455

Mitrano, Denise M; Rimmele, Elisa; Wichser, Adrian; Erni, Rolf; Height, Murray; Nowack, Bernd

2014-07-22

269

Phase transition of silver nanoparticles from aqueous solution to chloroform with the help of inclusion complexes of p-sulfonated calix[4]arene and alkanethiol molecules and its application in the size sorting of nanoparticles  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were synthesized in aqueous solution and capped with an inclusion complex of octadecanethiol (ODT) and p-sulfonated calix[4]arene (pSC4). By vigorous shaking of a biphasic mixture of the pSC4-threaded ODT-stabilized silver hydrosol and chloroform, the phase transition of the silver nanoparticles could be observed in the course of the transition of colour from the aqueous phase to the organic phase. The procedure of phase transition was independently verified by UV-vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, and 1H nuclear magnetic resonance (NMR). In shaking the biphasic mixture, it was believed that pSC4 molecules were desorbed from the inclusion complex and the protective layer of silver nanoparticles shifted from hydrophilic to hydrophobic, which drove the phase transition of silver nanoparticles from aqueous solution into chloroform. More interestingly, the efficiency in the phase transition of aqueous silver nanoparticles rigidly depended on their sizes, which maybe used in the size sorting of nanoparticles.

Chen, Ming; Diao, Guo Wang; Li, Chun Hui; Zhou, Xiao Ming

2007-05-01

270

Self-assembly of cinnamic acid-capped gold nanoparticles  

NASA Astrophysics Data System (ADS)

In this work, a new capping agent, cinnamic acid (CA) was used to synthesize Au nanoparticles (NPs) under ambient conditions. The size of the NPs can be controlled by adjusting the concentration of reductant (in our experiment sodium borohydride was used) or CA. The CA-stabilized Au NPs can self-assemble into 'nanowire-like' or 'pearl-necklace-like' nanostructures by adjusting the molar ratio of CA to HAuCl4 or by tuning the pH value of the Au colloidal solution. The process of Au NPs self-assembly was investigated by UV-vis spectroscopy and transmission electron microscopy. The results reveal that the induced dipole-dipole interaction is the driving force of Au NP linear assemblies.

Wang, Li; Wei, Gang; Sun, Lanlan; Liu, Zhiguo; Song, Yonghai; Yang, Tao; Sun, Yujing; Guo, Cunlan; Li, Zhuang

2006-06-01

271

Chitosan and silver nanoparticles: Promising anti-toxoplasma agents.  

PubMed

Toxoplasmosis is a worldwide infection caused by obligate intracellular protozoan parasite which is Toxoplasma gondii. Chitosan and silver nanoparticles were synthesized to be evaluated singly or combined for their anti-toxoplasma effects as prophylaxis and as treatment in the experimental animals. Results were assessed through studying the parasite density and the ultrastructural parasite changes, and estimation of serum gamma interferon. Weight of tissue silver was assessed in different organs. Results showed that silver nanoparticles used singly or combined with chitosan have promising anti-toxoplasma potentials. The animals that received these compounds showed statistically significant decrease in the mean number of the parasite count in the liver and the spleen, when compared to the corresponding control group. Light microscopic examination of the peritoneal exudates of animals receiving these compounds showed stoppage of movement and deformity in shape of the tachyzoites, whereas, by scanning electron microscope, the organisms were mutilated. Moreover, gamma interferon was increased in the serum of animals receiving these compounds. All values of silver detected in different tissues were within the safe range. Thus, these nanoparticles proved their effectiveness against the experimental Toxoplasma infection. PMID:24852215

Gaafar, M R; Mady, R F; Diab, R G; Shalaby, Th I

2014-08-01

272

Interaction between the surface of the silver nanoparticles prepared by ?-irradiation and organic molecules containing thiol group  

NASA Astrophysics Data System (ADS)

The colloidal silver nanoparticles were prepared by the ?-irradiation of silver nitrate (AgNO 3) in a mixture solution of water and 2-propanol in the presence of poly(vinylpyrrolidone) as a colloidal stabilizer. The Ag colloids obtained by ?-irradiation were characterized by use of XRD and TEM. The surface of the Ag colloids were modified by use of mercaptosuccinic acid (MSA), ( D)-cysteine (Cys), and ( L)-Cys, respectively. The MSA and ( L)-Cys-capped Ag colloids were aggregated because of hydrogen bonding of the carboxylic acid and amino acid group, respectively. From the analysis by CD spectroscopy, it was shown that chiral-enhanced phenomena were obtained in ( L)- and ( D)-Cys-capped Ag colloids.

Choi, Seong-Ho; Lee, Se-Hee; Hwang, Young-Mi; Lee, Kwang-Pill; Kang, Hee-Dong

2003-06-01

273

Self-Assembly of Tryptophan-Capped Gold Nanoparticles onto DNA Network Template  

Microsoft Academic Search

In this study, a simple route to the formation of DNA-gold complex has been reported, using immobilized DNA as a template. The nanoporous gold films have been prepared by the electrostatic self assembly of gold nanoparticles capped with tryptophan. Tryptophan would improve surface properties of gold nanoparticles for strongly attaching to DNA. Fourier transform infrared spectroscopy confirmed that gold nanoparticles

Zahra Sheikholeslami; Manouchehr Vosoughi

2009-01-01

274

Gold and silver nanoparticles for biomolecule immobilization and enzymatic catalysis  

PubMed Central

In this work, a simple method for alcohol synthesis with high enantiomeric purity was proposed. For this, colloidal gold and silver surface modifications with 3-mercaptopropanoic acid and cysteamine were used to generate carboxyl and amine functionalized gold and silver nanoparticles of 15 and 45?nm, respectively. Alcohol dehydrogenase from Thermoanaerobium brockii (TbADH) and its cofactor (NADPH) were physical and covalent (through direct adsorption and using cross-linker) immobilized on nanoparticles' surface. In contrast to the physical and covalent immobilizations that led to a loss of 90% of the initial enzyme activity and 98% immobilization, the use of a cross-linker in immobilization process promoted a loss to 30% of the initial enzyme activity and >92% immobilization. The yield of NADPH immobilization was about 80%. The best results in terms of activity were obtained with Ag-citr nanoparticle functionalized with carboxyl groups (Ag-COOH), Au-COOH(CTAB), and Au-citr functionalized with amine groups and stabilized with CTAB (Au-NH2(CTAB)) nanoparticles treated with 0.7% and 1.0% glutaraldehyde. Enzyme conformation upon immobilization was studied using fluorescence and circular dichroism spectroscopies. Shift in ellipticity at 222?nm with about 4 to 7?nm and significant decreasing in fluorescence emission for all bioconjugates were observed by binding of TbADH to silver/gold nanoparticles. Emission redshifting of 5?nm only for Ag-COOH-TbADH bioconjugate demonstrated change in the microenvironment of TbADH. Enzyme immobilization on glutaraldehyde-treated Au-NH2(CTAB) nanoparticles promotes an additional stabilization preserving about 50% of enzyme activity after 15?days storage. Nanoparticles attached-TbADH-NADPH systems were used for enantioselective (ee?>?99%) synthesis of (S)-7-hydroxy-2-tetralol.

2012-01-01

275

Gold and silver nanoparticles for biomolecule immobilization and enzymatic catalysis  

NASA Astrophysics Data System (ADS)

In this work, a simple method for alcohol synthesis with high enantiomeric purity was proposed. For this, colloidal gold and silver surface modifications with 3-mercaptopropanoic acid and cysteamine were used to generate carboxyl and amine functionalized gold and silver nanoparticles of 15 and 45 nm, respectively. Alcohol dehydrogenase from Thermoanaerobium brockii (TbADH) and its cofactor (NADPH) were physical and covalent (through direct adsorption and using cross-linker) immobilized on nanoparticles' surface. In contrast to the physical and covalent immobilizations that led to a loss of 90% of the initial enzyme activity and 98% immobilization, the use of a cross-linker in immobilization process promoted a loss to 30% of the initial enzyme activity and >92% immobilization. The yield of NADPH immobilization was about 80%. The best results in terms of activity were obtained with Ag-citr nanoparticle functionalized with carboxyl groups (Ag-COOH), Au-COOH(CTAB), and Au-citr functionalized with amine groups and stabilized with CTAB (Au-NH2(CTAB)) nanoparticles treated with 0.7% and 1.0% glutaraldehyde. Enzyme conformation upon immobilization was studied using fluorescence and circular dichroism spectroscopies. Shift in ellipticity at 222 nm with about 4 to 7 nm and significant decreasing in fluorescence emission for all bioconjugates were observed by binding of TbADH to silver/gold nanoparticles. Emission redshifting of 5 nm only for Ag-COOH-TbADH bioconjugate demonstrated change in the microenvironment of TbADH. Enzyme immobilization on glutaraldehyde-treated Au-NH2(CTAB) nanoparticles promotes an additional stabilization preserving about 50% of enzyme activity after 15 days storage. Nanoparticles attached-TbADH-NADPH systems were used for enantioselective ( ee > 99%) synthesis of ( S)-7-hydroxy-2-tetralol.

Petkova, Galina A.; Záruba, ?amil; Žvátora, Pavel; Král, Vladimír

2012-06-01

276

Surface enhanced Raman scattering of silver sensitized cobalt nanoparticles in metal dielectric nanocomposites  

Microsoft Academic Search

We report the preparation of a new type of nanocomposite containing cobalt and silver nanoparticles organized in parallel layers with a well controlled separation. This arrangement allows the observation of an enhanced low-frequency Raman signal at the vibration frequency of cobalt nanoparticles excited through the surface plasmons of silver nanoparticles. Numerical simulations of the electric field confirm the emergence of

J. Margueritat; J. Gonzalo; C. N. Afonso; U. Hörmann; G. Van Tendeloo; A. Mlayah; D. B. Murray; L. Saviot; Y. Zhou; M. H. Hong; B S Luk’yanchuk

2008-01-01

277

Numerical investigation of the plasmonic properties of bare and cysteine-functionalized silver nanoparticles  

Microsoft Academic Search

The absorption spectra of different aqueous dispersions containing silver nanoparticles were computed by finite element method and compared to spectra determined by UV-Visible spectroscopy. This comparative study proved that the spectrum measured on the aqueous dispersion of bare silver nanoparticles with absorptance maximum at lambdameas = 391 nm corresponds to the characteristic UV surface plasmon band of spherical nanoparticles with

Anikó Szalai; Áron Sipos; Viktória Hornok; László Tóth; Mária Csete; Imre Dékány

2011-01-01

278

Electrochemical detection of DNA hybridization based on silver-enhanced gold nanoparticle label  

Microsoft Academic Search

An electrochemical detection method for analyzing sequence-specific DNA using gold nanoparticle DNA probes and subsequent signal amplification step by silver enhancement is described. The assay relies on the electrostatic adsorption of target oligonucleotides onto the sensing surface of the glassy carbon electrode (GCE) and its hybridization to the gold nanoparticle-labeled oligonucleotides DNA probe. After silver deposition onto gold nanoparticles, binding

Hong Cai; Yanqing Wang; Pingang He; Yuzhi Fang

2002-01-01

279

Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro  

NASA Astrophysics Data System (ADS)

Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

Speshock, Janice L.; Braydich-Stolle, Laura K.; Szymanski, Eric R.; Hussain, Saber M.

2010-12-01

280

Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro  

NASA Astrophysics Data System (ADS)

Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

Speshock, Janice L.; Braydich-Stolle, Laura K.; Szymanski, Eric R.; Hussain, Saber M.

2011-12-01

281

Preparation and characterization of size controllable spherical silver nanoparticles  

NASA Astrophysics Data System (ADS)

By adjusting pH values of reactant system, the mass ratio of stabilizer/water and aging temperature, size controllable spherical silver nanoparticles (NPs) were synthesized. The properties of silver NPs are characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet visible (UV-VIS) absorption spectra. Within the pH values of 7.0-11.0, the aging temperature of 80 °C is better to improve silver NPs in shape to nearly sphere, concentrate size distribution and reduce aggregation than the aging temperature of 25 °C. The shape and dispersibility of silver NPs are the best when the pH of the reactant system is within 7.0-8.0. With pH of 7.5, aging at 80 °C, and stabilizer/water mass ratio of 1%, the spherical silver NPs with sizes of 50-70 nm were synthesized. The results are promising to be used to synthesize core/shell NPs when silver NPs are as core.

Yang, Ai-ling; Li, Shun-pin; Wang, Yu-jin; Bao, Xi-chang; Yang, Ren-qiang

2014-05-01

282

Synthesis of silver nanoparticles in methacrylic acid solution by gamma radiolysis and their application for estimation of dopamine at low concentrations  

NASA Astrophysics Data System (ADS)

Polymethacrylate capped silver nanoparticles have been synthesized in aqueous solution by gamma radiolysis method. The nanoparticle synthesis and polymerization of methacrylic acid occurred simultaneously in situ. Effect of different parameters such as precursor concentration and alkalinity on nanoparticle formation has been studied. These silver nanoparticles were tested for estimation of dopamine (DA) by monitoring surface plasmon band of nanoparticles at various DA concentrations. The result showed the response of spectral change towards DA concentration is linear in the DA concentration in the range of 5.27×10-7 to 1.58×10-5 mol dm-3. Also the interference of ascorbic acid (AA) in estimation of DA has also been studied. AA concentration up to 1.0×10-4 mol dm-3 does not interfere in the estimation of DA in the range of 5.27×10-7 to 1.05×10-5 mol dm-3.

Biswal, Jayashree; Misra, Nilanjal; Borde, Lalit C.; Sabharwal, S.

2013-02-01

283

Green synthesis of silver nanoparticles using cellulose extracted from an aquatic weed; water hyacinth.  

PubMed

As part of the desire to save the environment through "green" chemistry practices, we herein report an environmentally benign synthesis of silver nanoparticles (Ag-NPs) using cellulose extracted from an environmentally problematic aquatic weed, water hyacinth (WH), as both reducing and capping agent in an aqueous medium. By varying the pH of the solution and reaction time, the temporal evolutions of the optical and morphological properties of the as-synthesised Ag-NPs were investigated. The as-synthesised cellulose capped silver nanoparticles (C-Ag-NPs) were characterised using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The maximum surface plasmon resonance (SPR) peak decreased as the pH increased indicating that an increase in the pH of the solution favoured the formation of smaller particles. In addition, instantaneous change in the colour of the solution from colourless to brown within 5 min at pH 11 showed that the rate of reduction is faster at this pH compared to those at lower pH. The TEM micrographs showed that the materials are small, highly monodispersed and spherical in shape. The average particle mean diameters were calculated to be 5.69±5.89 nm, 4.53±1.36 nm and 2.68±0.69 nm nm at pH 4, 8 and 11 respectively. The HRTEM confirmed the crystallinity of the material while the FTIR spectra confirmed the capping of the as-synthesised Ag-NPs by the cellulose. It has been shown therefore that based on this synthetic method, this aquatic plant can be used to the advantage of mankind. PMID:23987347

Mochochoko, Tanki; Oluwafemi, Oluwatobi S; Jumbam, Denis N; Songca, Sandile P

2013-10-15

284

Tuning the electromagnetic field coupling between nanoporous silver and silver nanoparticles connected by hybridized oligonucleotide  

NASA Astrophysics Data System (ADS)

On monolithic nanoporous silver (NPS), via DNA hybridization, we constructed an NPS/DNA-Cy5/silver nanoparticle (Ag NP) sandwich to investigate its SERS effect. In this sandwich, no chemical enhancement contributes to the SERS signal of Cy5. As compared with NPS, the present substrate exhibits particularly strong electromagnetic (EM) field enhancement. At the same Ag NPs surface loading, the SERS intensity decreases exponentially with increasing the length of double-stranded DNA (dsDNA). A larger pore size of NPS leads to weaker EM enhancement within the sandwich, but the relative intensity is not sensitive to the sizes and it is determined by the length of dsDNA.

Zhao, Yin; Yan, Keqian; Huang, Xirong; Zhang, Zhonghua; Qu, Yinbo

2013-01-01

285

Banana peel extract mediated novel route for the synthesis of silver nanoparticles  

Microsoft Academic Search

Bio-inspired silver nanoparticles were synthesized with the aid of a novel, non-toxic, eco-friendly biological material namely, banana peel extract (BPE). Boiled, crushed, acetone precipitated, air-dried peel powder was used for reducing silver nitrate. Silver nanoparticles were formed when the reaction conditions were altered with respect to pH, BPE content, concentration of silver nitrate and incubation temperature. The colorless reaction mixtures

Ashok Bankar; Bhagyashree Joshi; Ameeta Ravi Kumar; Smita Zinjarde

2010-01-01

286

Synthesis and Study of Silver Nanoparticles  

ERIC Educational Resources Information Center

A laboratory experiment was conducted in which the students synthesized yellow colloidal silver, estimate particle size using visible spectroscopy and studied aggregation effects. The students were thus introduced to nanotechnology along with other topics such as redox chemistry, limiting and excess reactants, spectroscopy and atomic size.

Soloman, Sally D.; Bahadory, Mozghan; Jeyarajasingam, Aravindan V.; Rutkowsky, Susan A.; Boritz, Charles; Mulfinger, Lorraine

2007-01-01

287

Microwave-assisted synthesis of silver nanoparticles using benzo-18-crown-6 as reducing and stabilizing agent  

NASA Astrophysics Data System (ADS)

Benzo-18-crown-6 is employed to work as both reducing and stabilizing reagent in the reaction for synthesis of silver nanoparticles. Silver nanoparticles are analyzed using transmission electron microscope and UV-visible spectroscopic technique. The silver nanoparticles prepared in this way are uniform and stable, which can be stored at refrigerator for 5 months. Appearance of surface plasmon band at 420 nm indicated the formation of silver nanoparticles. Highly monodispersed stable silver nanoparticles were obtained within 3 min of microwave irradiation. Through transmission electron microscopy, silver nanoparticles were observed to be spherical.

Pal, Jolly; Deb, Manas Kanti; Deshmukh, Dhananjay Kumar

2014-04-01

288

In Situ Formation of Silver Nanoparticles within Chitosan-attached Cotton Fabric for Antibacterial Property  

Microsoft Academic Search

This work involves chemical modification of cotton fabrics by natural, biocompatible, and biodegradable polysaccharide — chitosan — followed by incorporating silver nanoparticles in the fabrics. The excellent chelating property of chitosan binds the silver metal ions that are later on reduced to nanoparticles giving rise to chitosan-attached nanosilver-loaded fabrics. The silver nanoparticles-loaded chitosan-attached fabric has been characterized by surface plasmon

Varsha Thomas; M. Bajpai; S. K. Bajpai

2011-01-01

289

Aerosol flow in a tube furnace reactor of gas-phase synthesised silver nanoparticles  

Microsoft Academic Search

In a previous work, gas-phase synthesis of silver nanoparticles through evaporation of silver powder and subsequent particle\\u000a nucleation by cooling was shown to be a viable method for achieving high purity silver nanoparticles (Backman et al. J Nanopart\\u000a Res 4:325–335, 2002). In order to control the size of the produced nanoparticles, careful design of the reactor is required with respect

D. Mitrakos; J. Jokiniemi; U. Backman; C. Housiadas

2008-01-01

290

Can silver nanoparticles be useful as potential biological labels?  

NASA Astrophysics Data System (ADS)

Silver (Ag) nanoparticles have unique plasmon-resonant optical scattering properties that are finding use in nanomedical applications such as signal enhancers, optical sensors, and biomarkers. In this study, we examined the chemical and biological properties of Ag nanoparticles of similar sizes, but that differed primarily in their surface chemistry (hydrocarbon versus polysaccharide), in neuroblastoma cells for their potential use as biological labels. We observed strong optical labeling of the cells in a high illumination light microscopy system after 24 h of incubation due to the excitation of plasmon resonance by both types of Ag nanoparticle. Surface binding of both types of Ag nanoparticle to the plasma membrane of the cells was verified with scanning electron microscopy as well as the internalization and localization of the Ag nanoparticles into intracellular vacuoles in thin cell sections with transmission electron microscopy. However, the induction of reactive oxygen species (ROS), degradation of mitochondrial membrane integrity, disruption of the actin cytoskeleton, and reduction in proliferation after stimulation with nerve growth factor were found after incubation with Ag nanoparticles at concentrations of 25 µg ml-1 or greater, with a more pronounced effect produced by the hydrocarbon-based Ag nanoparticles in most cases. Therefore, the use of Ag nanoparticles as potential biological labels, even if the surface is chemically modified with a biocompatible material, should be approached with caution.

Schrand, Amanda M.; Braydich-Stolle, Laura K.; Schlager, John J.; Dai, Liming; Hussain, Saber M.

2008-06-01

291

Novel synthesis of silver nanoparticles using 2,3,5,6-tetrakis-(morpholinomethyl) hydroquinone as reducing agent.  

PubMed

2,3,5,6-Tetrakis-(morpholinomethyl) hydroquinone (TMMH) was used as a reducing agent to synthesize spherical shaped silver nanoparticles in water-ethanol medium without using any stabilizing and capping agents. The reducing agent TMMH is prepared by Mannich-type reaction method and (1)H NMR, (13)C NMR and FT-IR spectroscopy techniques were used to characterize the compound (TMMH). The nature of bonding, structural and optical properties of the final product were analyzed using different techniques such as UV-Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The interaction between silver and reducing agent was confirmed by using FTIR analysis. The final product obtained showed higher crystallinity with cubic structure and an average crystalline size of about 20 nm. The results revealed that it is possible to synthesize crystalline Ag nanoparticles using organic compound as reducing agent. PMID:22542686

Manivel, P; Balamurugan, A; Ponpandian, N; Mangalaraj, D; Viswanathan, C

2012-09-01

292

Effect of Accelerator in Green Synthesis of Silver Nanoparticles  

PubMed Central

Silver nanoparticles (Ag-NPs) were successfully synthesized in the natural polymeric matrix. Silver nitrate, gelatin, glucose, and sodium hydroxide have been used as silver precursor, stabilizer, reducing agent, and accelerator reagent, respectively. This study investigated the role of NaOH as the accelerator. The resultant products have been confirmed to be Ag-NPs using powder X-ray diffraction (PXRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The colloidal sols of Ag-NPs obtained at different volumes of NaOH show strong and different surface plasmon resonance (SPR) peaks, which can be explained from the TEM images of Ag-NPs and their particle size distribution. Compared with other synthetic methods, this work is green, rapid, and simple to use. The newly prepared Ag-NPs may have many potential applications in chemical and biological industries.

Darroudi, Majid; Ahmad, Mansor Bin; Abdullah, Abdul Halim; Ibrahim, Nor Azowa; Shameli, Kamyar

2010-01-01

293

Stress-induced phase transformation and optical coupling of silver nanoparticle superlattices into mechanically stable nanowires.  

PubMed

One-dimensional silver materials display unique optical and electrical properties with promise as functional blocks for a new generation of nanoelectronics. To date, synthetic approaches and property engineering of silver nanowires have primarily focused on chemical methods. Here we report a simple physical method of metal nanowire synthesis, based on stress-induced phase transformation and sintering of spherical Ag nanoparticle superlattices. Two phase transformations of nanoparticles under stress have been observed at distinct length scales. First, the lattice dimensions of silver nanoparticle superlattices may be reversibly manipulated between 0-8?GPa compressive stresses to enable systematic and reversible changes in mesoscale optical coupling between silver nanoparticles. Second, stresses greater than 8?GPa induced an atomic lattice phase transformation, which induced sintering of silver nanoparticles into micron-length scale nanowires. The nanowire synthesis mechanism displays a dependence on both nanoparticle crystal surface orientation and presence of particular grain boundaries to enable nanoparticle consolidation into nanowires. PMID:24957078

Li, Binsong; Wen, Xiaodong; Li, Ruipeng; Wang, Zhongwu; Clem, Paul G; Fan, Hongyou

2014-01-01

294

Antibacterial Activity of pH-Dependent Biosynthesized Silver Nanoparticles against Clinical Pathogen  

PubMed Central

Simple, nontoxic, environmental friendly method is employed for the production of silver nanoparticles. In this study the synthesized nanoparticles UV absorption band occurred at 400?nm because of the surface Plasmon resonance of silver nanoparticles. The pH of the medium plays important role in the synthesis of control shaped and sized nanoparticles. The colour intensity of the aqueous solution varied with pH. In this study, at pH 9, the colour of the aqueous solution was dark brown, whereas in pH 5 the colour was yellowish brown; the colour difference in the aqueous solution occurred due to the higher production of silver nanoparticles. The antibacterial activity of biosynthesized silver nanoparticles was carried out against E. coli. The silver nanoparticles synthesized at pH 9 showed maximum antibacterial activity at 50??L.

Chitra, Kethirabalan; Annadurai, Gurusamy

2014-01-01

295

Biosynthesis of silver nanoparticles from Tribulus terrestris and its antimicrobial activity: a novel biological approach.  

PubMed

In the recent decades, increased development of green synthesis of nanoparticles is inevitable because of its incredible applications in all fields of science. There were numerous work have been produced based on the plant and its extract mediated synthesis of nanoparticles, in this present study to explore that the novel approaches for the biosynthesis of silver nanoparticles using plant fruit bodies. The plant, Tribulus terrestris L. fruit bodies are used in this study, where the dried fruit body extract was mixed with silver nitrate in order to synthesis of silver nanoparticles. The active phytochemicals present in the plant were responsible for the quick reduction of silver ion (Ag(+)) to metallic silver nanoparticles (Ag(0)). The reduced silver nanoparticles were characterized by Transmission Electron Microscope (TEM), Atomic Force Microscope (AFM), XRD, FTIR, UV-vis spectroscopy. The spherical shaped silver nanoparticles were observed and it was found to be 16-28 nm range of sizes. The diffraction pattern also confirmed that the higher percentage of silver with fine particles size. The antibacterial property of synthesized nanoparticles was observed by Kirby-Bauer method with clinically isolated multi-drug resistant bacteria such as Streptococcus pyogens, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus. The plant materials mediated synthesis of silver nanoparticles have comparatively rapid and less expensive and wide application to antibacterial therapy in modern medicine. PMID:22521683

Gopinath, V; MubarakAli, D; Priyadarshini, S; Priyadharsshini, N Meera; Thajuddin, N; Velusamy, P

2012-08-01

296

Plasmonic enhancement of a photocycloreversion reaction of a diarylethene derivative using individually dispersed silver nanoparticles.  

PubMed

The fabrication of silver nanoparticles covered with polymers with a well-defined core-shell structure and the quantitative evaluation of the plasmonic enhancement effect on a photochemical reaction in the vicinity of these silver nanoparticles individually dispersed in a medium are described. The photocycloreversion reaction of a diarylethene polymer in the vicinity of silver nanoparticles was enhanced by 2-6 times relative to the reaction without the nanoparticles. The promotion of the photocycloreversion reaction is due to enhancement of the electromagnetic field near the surface of the silver core. PMID:22945516

Nishi, Hiroyasu; Asahi, Tsuyoshi; Kobatake, Seiya

2012-11-12

297

Silver nanoparticles inhibit vaccinia virus infection by preventing viral entry through a macropinocytosis-dependent mechanism.  

PubMed

Silver nanoparticles have been shown to inhibit viruses. However, very little is known about the mechanism of antiviral activity. This study tested the hypothesis that 25-nm silver nanoparticles inhibited Vaccinia virus replication by preventing viral entry. Plaque reduction, confocal microscopy, and beta-galactosidase reporter gene assays were used to examine viral attachment and entry in the presence and absence of silver nanoparticles. To explore the mechanism of inhibition, viral entry experiments were conducted with silver nanoparticles and small interfering RNAs designed to silence the gene coding for p21-activated kinase 1, a key mediator of macropinocytosis. The silver nanoparticles caused a 4- to 5-log reduction in viral titer at concentrations that were not toxic to cells. Virus was capable of adsorbing to cells but could not enter cells in the presence of silver nanoparticles. Virus particles that had adsorbed to cells in the presence of silver nanoparticles were found to be infectious upon removal from the cells, indicating lack of direct virucidal effect. The half maximal inhibitory concentration for viral entry in the presence of silver nanoparticles was 27.4+/-3.3 microg/ml. When macropinocytosis was blocked, this inhibition was significantly reduced. Thus, macropinocytosis was required for the full antiviral effect. For the first time, this study points to the novel result that a cellular process involved in viral entry is responsible for the antiviral effects of silver nanoparticles. PMID:23980510

Trefry, John C; Wooley, Dawn P

2013-09-01

298

Potential sensing platform of silver nanoparticles embedded in functionalized silicate shell for nitroaromatic compounds.  

PubMed

A simple and new method to grow a pentagonally twinned structure of silver-silicate core-shell nanoparticles in aqueous environment at room temperature and its application in nitrobenzene (NB) sensing is described here. Silver-silicate core-shell nanoparticles were obtained by one-step synthesis using N-[3-(trimethoxysilyl)propyl]-ethylene diamine (EDAS) as a reducing/stabilizing agent and cetyltrimethylammonium bromide (CTAB) as the growing agent for the growth of silver nanoparticles (Ag(nps)). The silver-silicate core-shell nanoparticles were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible absorption, emission, excitation, and electrochemical measurements. The electrochemical studies of silver-silicate core-shell nanoparticles modified electrode showed the silver nanoparticle's oxidation potential and their corresponding reduction potential at 0.24 and -0.16 V, respectively. The optical and electrochemical applications silicate-shell stabilized silver nanoparticles were established toward nitrobenzene. The optical sensing of nitrobenzene by silver-silicate core-shell nanoparticles studied using absorption and emission spectral methods showed experimentally determined lowest detection limits (LOD) of 1 and 10 microM, respectively. Silver-silicate core-shell nanoparticles showed excellent electrocatalytic activity toward the reduction of nitrobenzene. The electrochemical sensor showed the lowest detection limit (LOD) of 2.5 nM toward nitrobenzene sensing. PMID:19691270

Maduraiveeran, Govindhan; Ramaraj, Ramasamy

2009-09-15

299

Proteomic analysis of silver nanoparticle toxicity in rat  

Microsoft Academic Search

Silver nanoparticles (SNPs) have received considerable attention recently, because SNPs with different shapes and sizes exhibit\\u000a variable antimicrobial activity, which makes them useful for medical and hygienic purposes. SNPs have been detected in various\\u000a tissues and organisms after inhalation, oral ingestion, and contact with the skin, indicating that SNPs can be distributed\\u000a to different body tissues after uptake. Thus, the

Eunjoo Kim; Young Chae Chu; Jee Young Han; Don Haeng Lee; Ye Ji Kim; Hyun-Chul Kim; Se Geun Lee; Sung Jun Lee; Sang Won Jeong; Joon Mee Kim

2010-01-01

300

Phytotoxicity of silver nanoparticles to Lemna minor L  

Microsoft Academic Search

The use of silver nanoparticles (AgNPs) in commercial products has increased significantly in recent years. Although there has been some attempt to determine the toxic effects of AgNPs, there is little information on aquatic plants which have a vital role in ecosystems. This study reports the use of Lemna minor L. clone St to investigate the phytotoxicity of AgNPs under

Eva J. Gubbins; Lesley C. Batty; Jamie R. Lead

2011-01-01

301

Silver nanoparticles: Green synthesis and their antimicrobial activities  

Microsoft Academic Search

This review presents an overview of silver nanoparticles (Ag NPs) preparation by green synthesis approaches that have advantages over conventional methods involving chemical agents associated with environmental toxicity. Green synthetic methods include mixed-valence polyoxometallates, polysaccharide, Tollens, irradiation, and biological. The mixed-valence polyoxometallates method was carried out in water, an environmentally-friendly solvent. Solutions of AgNO3 containing glucose and starch in water

Virender K. Sharma; Ria A. Yngard; Yekaterina Lin

2009-01-01

302

Syntheses and characterisation of silver nanoparticles in the acrylate copolymers  

Microsoft Academic Search

Silver nanoparticles were synthesised by polyol method using copolymer templates under microwave heating. The copolymer templates were synthesised by reacting the synthesised macromonomers with comonomer using free radical polymerisation. The copolymers were characterised by Fourier Transform InfraRed, H-NMR and C-NMR. The copolymers were further characterised by gel permeation chromatography for molecular weights and thermogravimetric analysis for thermal stability. These copolymers

S. Usha Rani; K. Jeeva Pandian; Boreddy S. R. Reddy

2009-01-01

303

The Role of Organic Capping Layers of Platinum Nanoparticles in Catalytic Activity of CO Oxidation  

SciTech Connect

We report the catalytic activity of colloid platinum nanoparticles synthesized with different organic capping layers. On the molecular scale, the porous organic layers have open spaces that permit the reactant and product molecules to reach the metal surface. We carried out CO oxidation on several platinum nanoparticle systems capped with various organic molecules to investigate the role of the capping agent on catalytic activity. Platinum colloid nanoparticles with four types of capping layer have been used: TTAB (Tetradecyltrimethylammonium Bromide), HDA (hexadecylamine), HDT (hexadecylthiol), and PVP (poly(vinylpyrrolidone)). The reactivity of the Pt nanoparticles varied by 30%, with higher activity on TTAB coated nanoparticles and lower activity on HDT, while the activation energy remained between 27-28 kcal/mol. In separate experiments, the organic capping layers were partially removed using ultraviolet light-ozone generation techniques, which resulted in increased catalytic activity due to the removal of some of the organic layers. These results indicate that the nature of chemical bonding between organic capping layers and nanoparticle surfaces plays a role in determining the catalytic activity of platinum colloid nanoparticles for carbon monoxide oxidation.

Park, Jeong Y.; Aliaga, Cesar; Renzas, J. Russell; Lee, Hyunjoo; Somorjai, Gabor A.

2008-12-17

304

Formation of sub-surface silver nanoparticles in silver-doped sodium-lead-germanate glass  

NASA Astrophysics Data System (ADS)

The formation of silver nanoparticles in 60GeO2-20PbO-20Na2O bulk glass doped with 0.15 wt% of Ag has been studied by optical methods in the near ultraviolet-to-near infrared and mid-infrared ranges. A clear optical absorption band, which grows when increasing the annealing temperature, is observed around 460 nm, as a consequence of the surface plasmon resonance in the Ag nanoparticles. From the simultaneous analysis of optical transmittance and spectroscopic ellipsometry spectra in the near ultraviolet-to-near infrared range, it is demonstrated that the nanoparticles are surprisingly formed only in a thin layer (some tens of nm thick) underneath the sample surfaces. The potential of such a simultaneous optical analysis for determining the localization of the nanoparticles in glasses of any nature is underlined. Based on the results of a complementary mid-infrared spectroscopy characterization, the processes involved in silver migration to the surfaces and further aggregation to form nanoparticles are discussed.

Fernández Navarro, J. M.; Toudert, J.; Rodríguez-Lazcano, Y.; Maté, B.; de Castro, M. Jiménez

2013-11-01

305

Characterization by spectroscopic Ellipsometry, the physical properties of silver nanoparticles.  

NASA Astrophysics Data System (ADS)

Physicists are able to change their minds through their experiments. I think it is time to go kick the curse and go further in research if we want a human future. I work in the Nano-Optics and Plasmonics research. I defined with ellipsomètrie the structure of new type of Nano particles of silver. It's same be act quickly to replace the old dirty leaded electronic-connexion chip and by the other hand to find a new way for the heath care of cancer disease by nanoparticles the next killers of bad cells. Silver nanoparticle layers are obtained by Spark Plasma Sintering are investigated as an alternative to lead alloy based material for solder joint in power mechatronics modules. These layers are characterized by mean of conventional techniques that is the dilatometry technique, the resistivity measurement through the van der Pauw method, and the flash laser technique. Furthermore, the nanoparticles of silver layer are deeply studied by UV-Visible spectroscopic ellipsometry. Spectroscopic angles parameters are determined in function of temperature and dielectric constants are deduced and analyzed through an optical model which takes into account a Drude and a Lorentz component within the Bruggeman effective medium approximation (EMA). The relaxation times and the electrical conductivity are plot in function of temperature. The obtained electrical conductivity give significant result in good agreement to those reported by four points electrical measurement method.

Coanga, Jean-Maurice

2013-04-01

306

Heterogeneous precipitation of silver nanoparticles on kaolinite plates  

NASA Astrophysics Data System (ADS)

Two different methods to obtain silver nanoparticles supported on kaolin crystals have been performed: the first one followed a thermal reduction and the second one a chemical reduction. In both cases, the silver nanoparticles with two different average particles size (ca.12 and 30 nm) were perfectly isolated and attached to the surface of the kaolin plates. The silver nanoparticles were localized mainly at the edge of the single crystal plates, the hydroxyl groups being the main centres of adsorption. The samples were fully characterized by XRD, UV-vis spectroscopy and TEM. The antimicrobial benefits of the composites were evaluated as antibacterial against common Gram-positive and Gram-negative bacteria, and antifungal activity against yeast. The results indicated a high antimicrobial activity for Escherichia coli JM 110 and Micrococcus luteus, while being inactive against yeast under our experimental conditions. The chemical analysis of Ag in the fermentation broths show that only a small portion of metal (<9 ppm) is released from the kaolin/metakaolin particles. Therefore, the risk of toxicity due to a high concentration of metal in the medium is minimized.

Cabal, B.; Torrecillas, R.; Malpartida, F.; Moya, J. S.

2010-11-01

307

Heterogeneous precipitation of silver nanoparticles on kaolinite plates.  

PubMed

Two different methods to obtain silver nanoparticles supported on kaolin crystals have been performed: the first one followed a thermal reduction and the second one a chemical reduction. In both cases, the silver nanoparticles with two different average particles size (ca.12 and 30 nm) were perfectly isolated and attached to the surface of the kaolin plates. The silver nanoparticles were localized mainly at the edge of the single crystal plates, the hydroxyl groups being the main centres of adsorption. The samples were fully characterized by XRD, UV-vis spectroscopy and TEM. The antimicrobial benefits of the composites were evaluated as antibacterial against common Gram-positive and Gram-negative bacteria, and antifungal activity against yeast. The results indicated a high antimicrobial activity for Escherichia coli JM 110 and Micrococcus luteus, while being inactive against yeast under our experimental conditions. The chemical analysis of Ag in the fermentation broths show that only a small portion of metal (<9 ppm) is released from the kaolin/metakaolin particles. Therefore, the risk of toxicity due to a high concentration of metal in the medium is minimized. PMID:21030755

Cabal, B; Torrecillas, R; Malpartida, F; Moya, J S

2010-11-26

308

Understanding the solvent polarity effects on surfactant-capped nanoparticles.  

PubMed

Understanding the molecular interactions between suspended nanoparticles (NPs) and the suspending solvent fluid may provide a useful avenue to create and to study exotic NP ensembles. This study focused on using a coarse-grained computational model to investigate the molecular interactions between oleate-capped NPs in various solvents, and to relate the results to experimental features of solvent-suspended, oleate-capped CdSe quantum dots (QDs). The QDs were modeled as a closed-shell fullerene molecule with an oleate-like ligand attached to each vertex. Solvent polarity was found to correlate to the simulation and experimental results more strongly than either dielectric constant or dipole moment. Computational results showed that the nonpolar solvents of hexane, toluene, and benzene (polarity index E(T)(N) < 0.120) kept NPs in suspension and solvated the oleate chains such that the oleate layer swelled to full extension. In contrast, as the most polar solvent tested (E(T)(N) = 1.000), water caused NPs to aggregate and precipitate. It partially solvated the oleate chains and compressed the layer to 86% of full extension. For solvents of intermediate polarity like ethanol, acetone, and chloroform, the oleate layer swelled with decreasing polarity index values, with rapid swelling occurring close to E(T)(N) = 0.307 (~50:50 vol % chloroform/acetone) below which QDs were colloidally stable. This study represents the first attempt to delineate the solvent effect on surfactant-coated NP hydrodynamic size, colloidal stability, and aggregation behavior. PMID:23088706

Leekumjorn, Sukit; Gullapalli, Sravani; Wong, Michael S

2012-11-01

309

Ultrafine silver nanoparticles obtained from ethylene glycol at room temperature: catalyzed by tungstate ions.  

PubMed

Ethylene glycol (EG) has been widely utilized to fabricate silver nanoparticles with uniform size and morphology. However, the majority of the work reported to date using EG routinely require not only heating, but also a surfactant. In the present paper, we report a surfactant-free and facile method for the synthesis of fairly monodisperse smaller silver nanoparticles (~6 nm) through the reaction of silver ions with EG by using tungstates (such as potassium tungstate, sodium tungstate) as catalysts at room temperature. Particularly, in this method, tungstates as catalysts can dramatically speed up the reduction of silver ions, and EG acts as both a solvent and a reducing agent to reduce silver ions to Ag metal. Meantime, we have carried out a series of experiments to investigate the performance of the as-prepared silver nanoparticles. It was found that the silver nanoparticles show excellent catalytic activity for the reduction of 4-nitrophenol in the presence of NaBH4. PMID:24100419

Li, Jin; Zhu, Junwu; Liu, Xiaoheng

2014-01-01

310

Synthesis and characterization of silver and gold nanoparticles in ionic liquid  

NASA Astrophysics Data System (ADS)

In this paper, we report the reduction of silver and gold salts by methanolic solution of sodium borohydride in tetrazolium based ionic liquid as a solvent at 30 °C leads to pure phase of silver and gold nanoparticles. Silver and gold nanoparticles so-prepared were well characterized by powder X-ray diffraction measurements (XRD), transmission electron microscopy (TEM) and QELS. XRD analysis revealed all relevant Bragg's reflection for crystal structure of silver and gold metal. XRD spectra also revealed no oxidation of silver nanoparticles to silver oxide. TEM showed nearly uniform distribution of the particles in methanol and it was confirmed by QELS. Silver and gold nanoparticles in ionic liquid can be easily synthesized and are quite stable too.

Singh, Prashant; Kumari, Kamlesh; Katyal, Anju; Kalra, Rashmi; Chandra, Ramesh

2009-07-01

311

Molecular recognition by gold, silver and copper nanoparticles  

PubMed Central

The intrinsic physical properties of the noble metal nanoparticles, which are highly sensitive to the nature of their local molecular environment, make such systems ideal for the detection of molecular recognition events. The current review describes the state of the art concerning molecular recognition of Noble metal nanoparticles. In the first part the preparation of such nanoparticles is discussed along with methods of capping and stabilization. A brief discussion of the three common methods of functionalization: Electrostatic adsorption; Chemisorption; Affinity-based coordination is given. In the second section a discussion of the optical and electrical properties of nanoparticles is given to aid the reader in understanding the use of such properties in molecular recognition. In the main section the various types of capping agents for molecular recognition; nucleic acid coatings, protein coatings and molecules from the family of supramolecular chemistry are described along with their numerous applications. Emphasis for the nucleic acids is on complementary oligonucleotide and aptamer recognition. For the proteins the recognition properties of antibodies form the core of the section. With respect to the supramolecular systems the cyclodextrins, calix[n]arenes, dendrimers, crown ethers and the cucurbitales are treated in depth. Finally a short section deals with the possible toxicity of the nanoparticles, a concern in public health.

Tauran, Yannick; Brioude, Arnaud; Coleman, Anthony W; Rhimi, Moez; Kim, Beonjoom

2013-01-01

312

Preparation and characterization of gelatin nanofibers containing silver nanoparticles.  

PubMed

Ag nanoparticles (NPs) were synthesized in formic acid aqueous solutions through chemical reduction. Formic acid was used for a reducing agent of Ag precursor and solvent of gelatin. Silver acetate, silver tetrafluoroborate, silver nitrate, and silver phosphate were used as Ag precursors. Ag+ ions were reduced into Ag NPs by formic acid. The formation of Ag NPs was characterized by a UV-Vis spectrophotometer. Ag NPs were quickly generated within a few minutes in silver nitrate (AgNO?)/formic acid solution. As the water content of formic acid aqueous solution increased, more Ag NPs were generated, at a higher rate and with greater size. When gelatin was added to the AgNO?/formic acid solution, the Ag NPs were stabilized, resulting in smaller particles. Moreover, gelatin limits further aggregation of Ag NPs, which were effectively dispersed in solution. The amount of Ag NPs formed increased with increasing concentration of AgNO? and aging time. Gelatin nanofibers containing Ag NPs were fabricated by electrospinning. The average diameters of gelatin nanofibers were 166.52 ± 32.72 nm, but these decreased with the addition of AgNO?. The average diameters of the Ag NPs in gelatin nanofibers ranged between 13 and 25 nm, which was confirmed by transmission electron microscopy (TEM). PMID:24758929

Jeong, Lim; Park, Won Ho

2014-01-01

313

Preparation and Characterization of Gelatin Nanofibers Containing Silver Nanoparticles  

PubMed Central

Ag nanoparticles (NPs) were synthesized in formic acid aqueous solutions through chemical reduction. Formic acid was used for a reducing agent of Ag precursor and solvent of gelatin. Silver acetate, silver tetrafluoroborate, silver nitrate, and silver phosphate were used as Ag precursors. Ag+ ions were reduced into Ag NPs by formic acid. The formation of Ag NPs was characterized by a UV-Vis spectrophotometer. Ag NPs were quickly generated within a few minutes in silver nitrate (AgNO3)/formic acid solution. As the water content of formic acid aqueous solution increased, more Ag NPs were generated, at a higher rate and with greater size. When gelatin was added to the AgNO3/formic acid solution, the Ag NPs were stabilized, resulting in smaller particles. Moreover, gelatin limits further aggregation of Ag NPs, which were effectively dispersed in solution. The amount of Ag NPs formed increased with increasing concentration of AgNO3 and aging time. Gelatin nanofibers containing Ag NPs were fabricated by electrospinning. The average diameters of gelatin nanofibers were 166.52 ± 32.72 nm, but these decreased with the addition of AgNO3. The average diameters of the Ag NPs in gelatin nanofibers ranged between 13 and 25 nm, which was confirmed by transmission electron microscopy (TEM).

Jeong, Lim; Park, Won Ho

2014-01-01

314

Low-cost silver capped polystyrene nanotube arrays as super-hydrophobic substrates for SERS applications  

NASA Astrophysics Data System (ADS)

In this paper, we describe the fabrication, simulation and characterization of dense arrays of freestanding silver capped polystyrene nanotubes, and demonstrate their suitability for surface enhanced Raman scattering (SERS) applications. Substrates are fabricated in a rapid, low-cost and scalable way by melt wetting of polystyrene (PS) in an anodized alumina (AAO) template, followed by silver evaporation. Scanning electron microscopy reveals that substrates are composed of a dense array of freestanding polystyrene nanotubes topped by silver nanocaps. SERS characterization of the substrates, employing a monolayer of 4-aminothiophenol (4-ABT) as a model molecule, exhibits an enhancement factor of ?1.6 × 106, in agreement with 3D finite difference time domain simulations. Contact angle measurements of the substrates revealed super-hydrophobic properties, allowing pre-concentration of target analyte into a small volume. These super-hydrophobic properties of the samples are taken advantage of for sensitive detection of the organic pollutant crystal violet, with detection down to ?400 ppt in a 2 ?l aliquot demonstrated.

Lovera, Pierre; Creedon, Niamh; Alatawi, Hanan; Mitchell, Micki; Burke, Micheal; Quinn, Aidan J.; O’Riordan, Alan

2014-05-01

315

Preferential Interaction of Na+ over K+ to Carboxylate-functionalized Silver Nanoparticles  

EPA Science Inventory

Elucidating mechanistic interactions between specific ions (Na+/ K+) and nanoparticle surfaces to alter particle stability in polar media has received little attention. We investigated relative preferential binding of Na+ and K+ to carboxylate-functionalized silver nanoparticles ...

316

Oral toxicity of silver ions, silver nanoparticles and colloidal silver--a review.  

PubMed

Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least a factor of five before a level of concern to the general population is reached. PMID:24231525

Hadrup, Niels; Lam, Henrik R

2014-02-01

317

Hydrogen-induced electrical and optical switching in Pd capped Pr nanoparticle layers  

Microsoft Academic Search

In this study, modification in the properties of hydrogen-induced switchable mirror based on Pr nanoparticle layers is reported.\\u000a The reversible changes in hydrogen-induced electrical and optical properties of Pd capped Pr nanoparticle layers have been\\u000a studied as a function of hydrogenation time and compared with the conventional device based on Pd capped Pr thin films. Faster\\u000a electrical and optical response,

Shubhra Kala; B. R. Mehta

2008-01-01

318

Green synthesis, optical properties and catalytic activity of silver nanoparticles in the synthesis of N-monosubstituted ureas in water  

NASA Astrophysics Data System (ADS)

We report the green synthesis of silver nanoparticles by using Euphorbia condylocarpa M. bieb root extract for the synthesis of N-monosubstituted ureas in water. UV-visible studies show the absorption band at 420 nm due to surface plasmon resonance (SPR) of the silver nanoparticles. This reveals the reduction of silver ions (Ag+) to silver (Ago) which indicates the formation of silver nanoparticles (Ag NPs). This method has the advantages of high yields, simple methodology and easy work up.

Nasrollahzadeh, Mahmoud; Babaei, Ferydon; Mohammad Sajadi, S.; Ehsani, Ali

2014-11-01

319

Origanum vulgare mediated biosynthesis of silver nanoparticles for its antibacterial and anticancer activity.  

PubMed

In the present study, we achieved silver nanoparticles using the aqueous extract of Origanum vulgare (Oregano) by reducing 1mM silver nitrate (AgNO3) solution. The green synthesized silver nanoparticles were characterized by high throughput techniques like UV-vis spectroscopy, Fourier infrared spectroscopy (FT-IR), field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and dynamic light scattering measurements. Morphologically, the nanoparticles were found to be spherical with an average particle size distribution of 136±10.09nm. FT-IR spectral analysis illustrates the occurrence of possible biomolecules required for the reduction of silver ions. The obtained nanoparticles were stable (-26±0.77mV) at ambient temperature. The biosynthesized nanoparticles were found to be impressive in inhibiting human pathogens. The green synthesized silver nanoparticles showed dose dependent response against human lung cancer A549 cell line (LD50 - 100?g/ml). PMID:23537829

Sankar, Renu; Karthik, Arunachalam; Prabu, Annamalai; Karthik, Selvaraju; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2013-08-01

320

Synthesis and characterization of agar-based silver nanoparticles and nanocomposite film with antibacterial applications.  

PubMed

This study describes the synthesis and characterization of silver nanoparticles and nanocomposite material using agar extracted from the red alga Gracilaria dura. Characterization of silver nanoparticles was carried out based on UV-Vis spectroscopy (421 nm), transmission electron microscopy, EDX, SAED and XRD analysis. The thermal stability of agar/silver nanocomposite film determined by TGA and DSC analysis showed distinct patterns when compared with their raw material (agar and AgNO(3)). The TEM findings revealed that the silver nanoparticles synthesized were spherical in shape, 6 nm in size with uniform dispersal. The synthesized nanoparticles had the great bactericidal activity with reduction of 99.9% of bacteria over the control value. The time required for synthesis of silver nanoparticles was found to be temperature dependent and higher the temperature less the time for nanoparticles formation. DSC and XRD showed approximately the same crystalline index (CI(DSC) 0.73). PMID:22244898

Shukla, Mahendra K; Singh, Ravindra Pal; Reddy, C R K; Jha, Bhavanath

2012-03-01

321

Silver nanoparticles: therapeutical uses, toxicity, and safety issues.  

PubMed

The promises of nanotechnology have been realized to deliver the greatest scientific and technological advances in several areas. The biocidal activity of Metal nanoparticles in general and silver nanoparticles (AgNPs) depends on several morphological and physicochemical characteristics of the particles. Many of the interactions of the AgNPs with the human body are still poorly understood; consequently, the most desirable characteristics for the AgNPs are not yet well established. Therefore, the development of nanoparticles with well-controlled morphological and physicochemical features for application in human body is still an active area of interdisciplinary research. Effects of the development of technology of nanostructured compounds seem to be so large and comprehensive that probably it will impact on all fields of science and technology. However, mechanisms of safety control in application, utilization, responsiveness, and disposal accumulation still need to be further studied in-depth to ensure that the advances provided by nanotechnology are real and liable to provide solid and consistent progress. This review aims to discuss AgNPs applied in biomedicine and as promising field for insertion and development of new compounds related to medical and pharmacy technology. The review also addresses drug delivery, toxicity issues, and the safety rules concerning biomedical applications of silver nanoparticles. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:1931-1944, 2014. PMID:24824033

Dos Santos, Carolina Alves; Seckler, Marcelo Martins; Ingle, Avinash P; Gupta, Indarchand; Galdiero, Stefania; Galdiero, Massimiliano; Gade, Aniket; Rai, Mahendra

2014-07-01

322

Silver nanoparticles dispersed in polyaniline matrixes coated on titanium substrate as a novel electrode for electro-oxidation of hydrazine  

Microsoft Academic Search

Silver nanoparticles dispersed in polyaniline matrixes coated on titanium substrate, as a novel electrode, was easily synthesized\\u000a by electro-polymerization of aniline on titanium and then electrodeposited silver nanoparticles on PAni electrode. The electrochemical\\u000a behavior and electro-catalytic activity of silver nanoparticles\\/PAni\\/Ti electrodes were characterized by cyclic voltammetry.\\u000a The morphology of silver nanoparticles on PAni\\/Ti electrodes were characterized by scanning electron microscopy

Mirghasem HosseiniMohamad; Mohamad Mohsen Momeni

2010-01-01

323

Substrates coated with silver nanoparticles as a neuronal regenerative material  

PubMed Central

Much effort has been devoted to the design of effective biomaterials for nerve regeneration. Here, we report the novel use of silver nanoparticles (AgNPs) as regenerative agents to promote neuronal growth. We grew neuroblastoma cells on surfaces coated with AgNPs and studied the effect on the development of the neurites during the initiation and the elongation growth phases. We find that the AgNPs function as favorable anchoring sites, and the growth on the AgNP-coated substrates leads to a significantly enhanced neurite outgrowth. Cells grown on substrates coated with AgNPs have initiated three times more neurites than cells grown on uncoated substrates, and two times more than cells grown on substrates sputtered with a plain homogenous layer of silver. The growth of neurites on AgNPs in the elongation phase was enhanced as well. A comparison with substrates coated with gold nanoparticles (AuNPs) and zinc oxide nanoparticles (ZnONPs) demonstrated a clear silver material-driven promoting effect, in addition to the nanotopography. The growth on substrates coated with AgNPs has led to a significantly higher number of initiating neurites when compared to substrates coated with AuNPs or ZnONPs. All nanoparticle-coated substrates affected and promoted the elongation of neurites, with a significant positive maximal effect for the AgNPs. Our results, combined with the well-known antibacterial effect of AgNPs, suggest the use of AgNPs as an attractive nanomaterial – with dual activity – for neuronal repair studies.

Alon, Noa; Miroshnikov, Yana; Perkas, Nina; Nissan, Ifat; Gedanken, Aharon; Shefi, Orit

2014-01-01

324

Substrates coated with silver nanoparticles as a neuronal regenerative material.  

PubMed

Much effort has been devoted to the design of effective biomaterials for nerve regeneration. Here, we report the novel use of silver nanoparticles (AgNPs) as regenerative agents to promote neuronal growth. We grew neuroblastoma cells on surfaces coated with AgNPs and studied the effect on the development of the neurites during the initiation and the elongation growth phases. We find that the AgNPs function as favorable anchoring sites, and the growth on the AgNP-coated substrates leads to a significantly enhanced neurite outgrowth. Cells grown on substrates coated with AgNPs have initiated three times more neurites than cells grown on uncoated substrates, and two times more than cells grown on substrates sputtered with a plain homogenous layer of silver. The growth of neurites on AgNPs in the elongation phase was enhanced as well. A comparison with substrates coated with gold nanoparticles (AuNPs) and zinc oxide nanoparticles (ZnONPs) demonstrated a clear silver material-driven promoting effect, in addition to the nanotopography. The growth on substrates coated with AgNPs has led to a significantly higher number of initiating neurites when compared to substrates coated with AuNPs or ZnONPs. All nanoparticle-coated substrates affected and promoted the elongation of neurites, with a significant positive maximal effect for the AgNPs. Our results, combined with the well-known antibacterial effect of AgNPs, suggest the use of AgNPs as an attractive nanomaterial - with dual activity - for neuronal repair studies. PMID:24872701

Alon, Noa; Miroshnikov, Yana; Perkas, Nina; Nissan, Ifat; Gedanken, Aharon; Shefi, Orit

2014-01-01

325

Reversible transformations of silver oxide and metallic silver nanoparticles inside SiO{sub 2} films  

SciTech Connect

Reversible transformation of silver oxide and metallic nanoparticles inside a relatively porous silica film has been established. Annealing of Ag-doped films in oxidizing (air) atmosphere at 450 deg. C yielded colorless films containing AgO{sub x}. These films were turned yellow when heated in H{sub 2}-N{sub 2} (reducing atmosphere) due to the formation of Ag nanoparticles. This yellow coloration (due to nano Ag{sup 0}) and bleaching (conversion of Ag{sup 0} {yields} Ag{sup +}) are reversible. Optical and photoluminescence spectra are well consistent with this coloration and bleaching. The soaking test of the air-annealed film in Na{sub 2}S{sub 2}O{sub 3} solution supports the presence of Ag{sup +}. Grazing incidence X-ray diffraction and transmission electron microscopy studies reveal the formation of Ag-oxides and Ag nanoparticles in the oxidized and reduced films, respectively.

Pal, Sudipto [Sol-Gel Division, Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Jadavpur, Kolkata 700032 (India); De, Goutam [Sol-Gel Division, Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Jadavpur, Kolkata 700032 (India)], E-mail: gde@cgcri.res.in

2009-02-04

326

Evaluation of a Silver Nanoparticle Generator Using a Small Ceramic Heater for Inactivation of S. epidermidis Bioaerosols  

Microsoft Academic Search

Silver has been known to show antibacterial activity. Recently, silver nanoparticles have been become widely used in diverse applications. In a previous work by the authors, a small nanoparticle generator that uses a ceramic heater with a local heating area was developed. The performance of the device was evaluated in terms of the silver nanoparticles it generated. In the present

Jun Ho Ji; Gwi-Nam Bae; Sun Hwa Yun; Jae Hee Jung; Hyung Soo Noh; Sang Soo Kim

2007-01-01

327

Silver nanoparticle-specific mitotoxicity in Daphnia magna.  

PubMed

Silver nanoparticles (Ag NPs) are gaining popularity as bactericidal agents in commercial products; however, the mechanisms of toxicity (MOT) of Ag NPs to other organisms are not fully understood. It is the goal of this research to determine differences in MOT induced by ionic Ag(+) and Ag NPs in Daphnia magna, by incorporating a battery of traditional and novel methods. Daphnia embryos were exposed to sublethal concentrations of AgNO3 and Ag NPs (130-650 ng/L), with uptake of the latter confirmed by confocal reflectance microscopy. Mitochondrial function was non-invasively monitored by measuring proton flux using self-referencing microsensors. Proton flux measurements revealed that while both forms of silver significantly affected proton efflux, the change induced by Ag NPs was greater than that of Ag(+). This could be correlated with the effects of Ag NPs on mitochondrial dysfunction, as determined by confocal fluorescence microscopy and JC-1, an indicator of mitochondrial permeability. However, Ag(+) was more efficient than Ag NPs at displacing Na(+) within embryonic Daphnia, based on inductively coupled plasma-mass spectroscopy (ICP-MS) analysis. The abnormalities in mitochondrial activity for Ag NP-exposed organisms suggest a nanoparticle-specific MOT, distinct from that induced by Ag ions. We propose that the MOT of each form of silver are complementary, and can act in synergy to produce a greater toxic response overall. PMID:23927462

Stensberg, Matthew C; Madangopal, Rajtarun; Yale, Gowri; Wei, Qingshan; Ochoa-Acuña, Hugo; Wei, Alexander; McLamore, Eric S; Rickus, Jenna; Porterfield, D Marshall; Sepúlveda, Maria S

2014-12-01

328

Green synthesis of hyaluronan fibers with silver nanoparticles.  

PubMed

The application of green chemistry in the nano-science and technology is very important in the area of the preparation of various materials. In this work, an eco-friendly chemical method was successfully used for the preparation of hyaluronan fibers containing silver nanoparticles (AgNPs). Thus, hyaluronic acid (HA) was dissolved in an aqueous solution of sodium hydroxide to prepare a transparent solution, which was used for the preparation of fibers by a wet-spinning technique. Consequently, silver nanoparticles inside the fiber were prepared. Different parameters affecting the preparation of final product, such as concentration of silver nitrate, hyaluronan fiber concentration, time and temperature of the reaction, pH of the reaction mixture, were studied. AgNPs were confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD), two-dimensional X-ray scattering (2D SWAXS), UV/Vis spectroscopy, inductively coupled plasma optical emission spectrometry (ICP OES) and scan electron microscopy (SEM). Mechanical properties of prepared fibers were also measured. PMID:24750738

Abdel-Mohsen, A M; Hrdina, Radim; Burgert, Ladislav; Krylová, Gabriela; Abdel-Rahman, Rasha M; Krej?ová, Anna; Steinhart, Miloš; Beneš, Ludvík

2012-06-20

329

Stability, size and optical properties of colloidal silver nanoparticles prepared by electrical arc discharge in water  

Microsoft Academic Search

We have fabricated and characterised colloidal silver nanoparticles by the electrical arc discharge method in DI water. Size and optical properties of the silver nanoparticles were studied versus different arc currents. Optical absorption indicates a plasmonic peak at 392 nm for 10 A which increases to 398 nm for 20 A arc current. This reveals that by raising the arc

A. A. Ashkarran; A. Iraji Zad; M. M. Ahadian; M. R. Hormozi Nezhad

2009-01-01

330

Characterization of silver nanoparticle-infused tissue adhesive for ophthalmic use  

NASA Astrophysics Data System (ADS)

This research examined if the infusion of silver nanoparticles into a 2-octyl cyanoacrylate tissue adhesive alters the antibacterial effectiveness and mechanical properties of the adhesive. Silver nanoparticle size and concentration combinations were varied to determine the effects of these factors. Uniform distribution of the silver nanoparticles was achieved before proceeding to testing. Antibacterial effectiveness of the composite adhesive was determined via the Kirby-Bauer disk diffusion susceptibility test and by CFU counting. Doping the adhesive with silver nanoparticles resulted in an order of magnitude reduction in bacterial growth. The greatest antibacterial effect came from imbuing 10 microg/mL of 4 nm silver nanoparticles into the tissue adhesive. Despite the noticeable reduction of bacterial growth for the doped adhesives, the difference among the varying silver nanoparticle size and concentration combinations was minimal. The breaking strength of the adhesive increased when silver nanoparticles were added. The adhesive strength of the composite adhesive attached to an incised porcine sclera was also greater than the unaltered adhesive. The greatest breaking load and adhesive force was the 10 microg/mL of 10 nm silver nanoparticle-doped adhesive. The increased mechanical strength of the doped adhesive expands the possible applications of treatment on different areas of the body.

Yee, William

331

Utilization of silver nanoparticles as chlorine-free biocide for water treatment  

Microsoft Academic Search

The objective of this research is to elucidate the main disinfectant mechanism of nanosilver and to evaluate its interaction with the biological, chemical and physical components of natural waters. Silver nanoparticles interact differently with different dissolved and particulate compounds commonly present in drinking water depending upon the disinfectant mechanism. Our preliminary results show that concentrations of silver nanoparticles below 5

Vinka Craver

332

Amperometric Sensor Used for Determination of Thiocyanate with a Silver Nanoparticles Modified Electrode  

PubMed Central

A novel electrode modified with silver nanoparticles was fabricated. It is found that the reducibility of silver nanoparticles is higher than for bulk silver by comparing a silver nanoparticles modified electrode with a silver micro-disk electrode. When SCN- was added, a new oxidation peak occurred and the anodic peak current of silver nanoparticles decreased. The new anodic peak current is proportional to the thiocyanate concentration in the range of 5.0×10-7?4.0×10-4 mol/L in pH 6.0 NaH2PO4-Na2HPO4 buffer solutions (PBS). The detection limit (S/N=3) is 4×10-8 mol/L. This method has been applied to the determination of saliva (smoker and non-smoker).

Wang, Guang-Feng; Li, Mao-Guo; Gao, Ying-Chun; Fang, Bin

2004-01-01

333

Synthesis, characterization and evaluation of silver nanoparticles through leaves of Abrus precatorius L.: an important medicinal plant  

NASA Astrophysics Data System (ADS)

Biologically synthesized nanoparticles have been widely used in the field of medicine. The present study reports the green synthesis of silver nanoparticles using Abrus precatorius leaf extract with silver nitrate solution as reducing agent. The synthesized silver nanoparticles were analyzed through UV-Visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, atomic force microscopy and Fourier transform infrared. The synthesized silver nanoparticles were disk shaped with an average size of 19 nm. These silver nanoparticles were evaluated for antibacterial activity. The diameter of inhibition zones around the disk of Pseudomonas aeruginosa and Staphylococcus aureus are resistant to silver nanoparticles, whereas Escherichia coli and Bacillus thuringiensis are susceptible when compared with the other two species. The results were compared with the ciprofloxacin-positive control and silver nitrate. It is concluded that the green synthesis of silver nanoparticles is very fast, easy, cost-effective and eco-friendly and without any side effects.

Gaddala, Bhumi; Nataru, Savithramma

2014-03-01

334

Fabrication Of Biogenic Silver Nanoparticles Using Agricultural Crop Plant Leaf Extracts  

NASA Astrophysics Data System (ADS)

Nanoparticles are being viewed as fundamental building blocks of nanotechnology. Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Use of agricultural crop plant extracts for synthesis of metal nanoparticles would add a new dimension to the agricultural sector in the utilization of crop waste. Silver has long been recognized as having an inhibitory effect towards many bacterial strains and microorganisms commonly present in medical and industrial processes. Four pulse crop plants and three cereal crop plants (Vigna radiata, Arachis hypogaea, Cyamopsis tetragonolobus, Zea mays, Pennisetum glaucum, Sorghum vulgare) were used and compared for their extra cellular synthesis of metallic silver nanoparticles. Stable silver nanoparticles were formed by treating aqueous solution of AgNO3 with the plant leaf extracts as reducing agent at temperatures 50 °C-95 °C. UV-Visible spectroscopy was utilized to monitor the formation of silver nanoparticles. XRD analysis of formed silver nanoparticles revealed face centered cubic structure with (111), (200), (220) and (311) planes. SEM and EDAX analysis confirm the size of the formed silver nanoparticles to be in the range of 50-200 nm. Our proposed work offers a enviro-friendly method for biogenic silver nanoparticles production. This could provide a faster synthesis rate comparable to those of chemical methods and potentially be used in areas such as cosmetics, food and medical applications.

Rajani, P.; Srisindhura, K.; Prasad, T. N. V. K. V.; Hussain, O. M.; Sudhakar, P.; Latha, P.; Balakrishna, M.; Kambala, V.; Reddy, K. Raja

2010-10-01

335

Silver nanoparticles: mechanism of antimicrobial action, synthesis, medical applications, and toxicity effects  

NASA Astrophysics Data System (ADS)

Silver nanoparticles are nanoparticles of silver which are in the range of 1 and 100 nm in size. Silver nanoparticles have unique properties which help in molecular diagnostics, in therapies, as well as in devices that are used in several medical procedures. The major methods used for silver nanoparticle synthesis are the physical and chemical methods. The problem with the chemical and physical methods is that the synthesis is expensive and can also have toxic substances absorbed onto them. To overcome this, the biological method provides a feasible alternative. The major biological systems involved in this are bacteria, fungi, and plant extracts. The major applications of silver nanoparticles in the medical field include diagnostic applications and therapeutic applications. In most of the therapeutic applications, it is the antimicrobial property that is being majorly explored, though the anti-inflammatory property has its fair share of applications. Though silver nanoparticles are rampantly used in many medical procedures and devices as well as in various biological fields, they have their drawbacks due to nanotoxicity. This review provides a comprehensive view on the mechanism of action, production, applications in the medical field, and the health and environmental concerns that are allegedly caused due to these nanoparticles. The focus is on effective and efficient synthesis of silver nanoparticles while exploring their various prospective applications besides trying to understand the current scenario in the debates on the toxicity concerns these nanoparticles pose.

Prabhu, Sukumaran; Poulose, Eldho K.

2012-10-01

336

Novel, silver-ion-releasing nanofibrous scaffolds exhibit excellent antibacterial efficacy without the use of silver nanoparticles.  

PubMed

Nanofibers, with their morphological similarities to the extracellular matrix of skin, hold great potential for skin tissue engineering. Over the last decade, silver nanoparticles have been extensively investigated in wound-healing applications for their ability to provide antimicrobial benefits to nanofibrous scaffolds. However, the use of silver nanoparticles has raised concerns as these particles can penetrate into the stratum corneum of skin, or even diffuse into the cellular plasma membrane. We present and evaluate a new silver ion release polymeric coating that we have found can be applied to biocompatible, biodegradable poly(l-lactic acid) nanofibrous scaffolds. Using this compound, custom antimicrobial silver-ion-releasing nanofibers were created. The presence of a uniform, continuous silver coating on the nanofibrous scaffolds was verified by XPS analysis. The antimicrobial efficacy of the antimicrobial scaffolds against Staphylococcus aureus and Escherichia coli bacteria was determined via industry-standard AATCC protocols. Cytotoxicity analyses of the antimicrobial scaffolds toward human epidermal keratinocytes and human dermal fibroblasts were performed via quantitative analyses of cell viability and proliferation. Our results indicated that the custom antimicrobial scaffolds exhibited excellent antimicrobial properties while also maintaining human skin cell viability and proliferation for silver ion concentrations below 62.5?gml(-1) within the coating solution. This is the first study to show that silver ions can be effectively delivered with nanofibrous scaffolds without the use of silver nanoparticles. PMID:24365706

Mohiti-Asli, Mahsa; Pourdeyhimi, Behnam; Loboa, Elizabeth G

2014-05-01

337

Biosynthesis of Silver Nanoparticles from Marine Seaweed Sargassum cinereum and their Antibacterial Activity.  

PubMed

Seaweed extracts of Sargassum cinereum was used as a reducing agent in the eco-friendly extracellular synthesis of silver nanoparticles from an aqueous solution of silver nitrate (AgNO3). High conversion of silver ions to silver nanoparticles was achieved with a reaction temperature of 100(°) and a seaweed extract concentration of 10% with a residential time of 3 h. Formation of silver nanoparticles was characterised by spectrophotometry and the scanning electron microscope. The average particles size was ranging from 45 to 76 nm. Antimicrobial activities indicate the minimum inhibitory concentration of biologically synthesised nanoparticles tested against the pathogen Staphylococcus aureus with 2.5 ?l (25 ?g/disc). High inhibitions over the growth of Enterobacter aerogenes, Salmonella typhi and Proteus vulgaris were witnessed against the concentrations of 100 ?g/disc. Promising potential and the future prospects of S. cinereum nanoparticles in pharmaceutical research are the highlights in this paper. PMID:24403664

Mohandass, C; Vijayaraj, A S; Rajasabapathy, R; Satheeshbabu, S; Rao, S V; Shiva, C; De-Mello, I

2013-09-01

338

Biosynthesis of Silver Nanoparticles from Marine Seaweed Sargassum cinereum and their Antibacterial Activity  

PubMed Central

Seaweed extracts of Sargassum cinereum was used as a reducing agent in the eco-friendly extracellular synthesis of silver nanoparticles from an aqueous solution of silver nitrate (AgNO3). High conversion of silver ions to silver nanoparticles was achieved with a reaction temperature of 100° and a seaweed extract concentration of 10% with a residential time of 3 h. Formation of silver nanoparticles was characterised by spectrophotometry and the scanning electron microscope. The average particles size was ranging from 45 to 76 nm. Antimicrobial activities indicate the minimum inhibitory concentration of biologically synthesised nanoparticles tested against the pathogen Staphylococcus aureus with 2.5 ?l (25 ?g/disc). High inhibitions over the growth of Enterobacter aerogenes, Salmonella typhi and Proteus vulgaris were witnessed against the concentrations of 100 ?g/disc. Promising potential and the future prospects of S. cinereum nanoparticles in pharmaceutical research are the highlights in this paper.

Mohandass, C.; Vijayaraj, A. S.; Rajasabapathy, R.; Satheeshbabu, S.; Rao, S. V.; Shiva, C.; De-Mello, I.

2013-01-01

339

Influence of silver nanoparticles on neurons and blood-brain barrier via subcutaneous injection in rats  

NASA Astrophysics Data System (ADS)

Nanosilver has been widely used in medical biology; however, the distribution and interaction of nanosilver with cells is still unclear. There have been some reports demonstrating that nanoparticles can cross the blood-brain barrier (BBB). The present study investigated the accumulation of silver nanoparticles in the brain, and the effects of silver nanoparticles on BBB. Nanosilver and microsilver (62.8 mg/kg) particles were subcutaneously injected into rats. The rats were sacrificed at predetermined time points and the brains were obtained for ultrastructural observation and silver level detection. The results showed that silver nanoparticles could traverse the BBB and move into the brain in the form of particle. The silver nanoparticles can induce neuronal degeneration and necrosis by accumulating in the brain over a long period of time.

Tang, Jinglong; Xiong, Ling; Wang, Shuo; Wang, Jianyu; Liu, Li; Li, Jiage; Wan, Ziyi; Xi, Tingfei

2008-11-01

340

Green Synthesis of Silver Nanoparticles Using Neem Leaf (Azadirachta indica) Extract  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were successfully synthesized using crude neem leaf (Azadirachta indica) extract at room temperature. The formation and crystallinity of synthesized silver nanoparticles was confirmed by X-Ray diffraction (XRD) pattern. The average size of these silver nanoparticles is about 20-50 nm as observed by Transmission electron microscopy (TEM) images. Optical absorption measurements were performed to determine band-edge energy gap of these silver nanoparticles. Photoluminescence (PL) studies were performed to emphasize its emission properties. The synthesized silver nanoparticles could have major applications in the area of nanoscale optoelectronics devices and biomedical engineering. Our synthesis method has advantage over other conventional chemical routes because it is cost effective & environmental compatibility.

Shukla, Vineet Kumar; Pandey, Shipra; Pandey, Avinash C.

2010-10-01

341

Deposition of hexagonal boron nitride thin films on silver nanoparticle substrates and surface enhanced infrared absorption  

NASA Astrophysics Data System (ADS)

Silver nanoparticle thin films with different average particle diameters are grown on silicon substrates. Boron nitride thin films are then deposited on the silver nanoparticle interlayers by radio frequency (RF) magnetron sputtering. The boron nitride thin films are characterized by Fourier transform infrared spectra. The average particle diameters of silver nanoparticle thin films are 126.6, 78.4, and 178.8 nm. The results show that the sizes of the silver nanoparticles have effects on the intensities of infrared spectra of boron nitride thin films. An enhanced infrared absorption is detected for boron nitride thin film grown on silver nanoparticle thin film. This result is helpful to study the growth mechanism of boron nitride thin film.

Deng, Jin-Xiang; Chen, Liang; Man, Chao; Kong, Le; Cui, Min; Gao, Xue-Fei

2014-04-01

342

Influence of silver nanoparticles on food components in wheat  

NASA Astrophysics Data System (ADS)

During storage, grain might be affected by bacterial and fungal infections. Pathogens diminish the grain quality through contamination with excrements and second metabolites. It is very important to prevent grain from infections. Due to their antimicrobial properties, silver nanoparticles can play the role of an effective protector. The influence of nanoparticles on wheat quality was studied. The gluten parameters and falling number did not change after covering the grain with silver nanoparticles stabilized by sodium citrate. Changes in the structure of starch and gluten were investigated using Fourier-transform infrared spectroscopy. Infrared spectra of the whole meal and starch have shown a slight shift (from 1 000 to 995cm-1) of the band connected with the C-O-H bending. This displacement is probably related to the changes in sample moisture. Significant differences, corresponding to changes in the protein secondary structure, have appeared in the gluten spectra after covering.A decrease of absorbance in the amide and CH and OH regions has been observed regardless of the covering time.

Nawrocka, A.; Cie?la, J.

2013-01-01

343

Toxicity effect of silver nanoparticles in brine shrimp Artemia.  

PubMed

The present study revealed the toxic effect of silver nanoparticles (AgNPs) in Artemia nauplii and evaluated the mortality rate, hatching percentage, and genotoxic effect in Artemia nauplii/cysts. The AgNPs were commercially purchased and characterized using field emission scanning electron microscope with energy dispersive X-ray spectroscopy. Nanoparticles were spherical in nature and with size range of 30-40 nm. Artemia cysts were collected from salt pan, processed, and hatched in sea water. Artemia nauplii (II instar) were treated using silver nanoparticles of various nanomolar concentrations and LC50 value (10 nM) and mortality rate (24 and 48 hours) was evaluated. Hatching percentage of decapsulated cysts treated with AgNPs was examined. Aggregation of AgNPs in the gut region of nauplii was studied using phase contrast microscope and apoptotic cells in nauplii stained with acridine orange were observed using fluorescence microscope. DNA damage of single cell of nauplii was determined by comet assay. This study showed that as the concentration of AgNPs increased, the mortality rate, aggregation in gut region, apoptotic cells, and DNA damage increased in nauplii, whereas the percentage of hatching in Artemia cysts decreased. Thus this study revealed that the nanomolar concentrations of AgNPs have toxic effect on both Artemia nauplii and cysts. PMID:24516361

Arulvasu, Chinnasamy; Jennifer, Samou Michael; Prabhu, Durai; Chandhirasekar, Devakumar

2014-01-01

344

Synthesis of Silver Nanoparticles by a Laser–Liquid–Solid Interaction Technique  

Microsoft Academic Search

Silver nanoparticles of high chemical homogeneity have been synthesized by a novel laser–liquid–solid interaction technique from a solution composed of silver nitrate, distilled water, ethylene glycol, and diethylene glycol. Rotating nickel, niobium, stainless steel, and ceramic Al2O3 substrates were irradiated using a continuous-wave CO2 laser and Q-switched Nd–YAG laser (? = 1064 and 532 nm). The silver nanoparticles were characterized

D. Poondi; R. Subramanian; M. Otooni; J. Singh

1998-01-01

345

Preparation, characterization and cytotoxicity of schizophyllan/silver nanoparticle composite.  

PubMed

Silver nanoparticles (Ag-NPs) have been successfully prepared with a simple and "green" chemical reduction method. Triple helical schizophyllan (SPG) was used for the first time as reducing and stabilizing agents. The effect of temperature, silver nitrate/schizophyllan concentrations, pH of the reactions medium and the reaction time were investigated. The obtained schizophyllan/Ag-NP was characterized by UV-vis spectroscopy, TEM, DLS, X-ray diffraction, TGA, and ATR-FTIR. The results revealed that, Ag-NPs attached to SPG through a strong non-covalent interaction, leading to good dispersion of Ag-NPs with a diameter of 6 nm within the biopolymer matrix. By increasing the pH of the reaction medium, the triple helical structure of SPG was partially broken. The SPG/AgNP nanocomposite was non-toxic for mouse fibroblast line (NIH-3T3) and human keratinocyte cell line (HaCaT). PMID:24507278

Abdel-Mohsen, A M; Abdel-Rahman, Rasha M; Fouda, Moustafa M G; Vojtova, L; Uhrova, L; Hassan, A F; Al-Deyab, Salem S; El-Shamy, Ibrahim E; Jancar, J

2014-02-15

346

Biogenic silver nanoparticles for cancer treatment: an experimental report.  

PubMed

A generation of nanoparticles research has discussed recently. It is mandatory to elaborate the applications of biogenic nanoparticles in general and anticancereous property in particular. The present study was aimed to investigate the in vitro cytotoxicity effect of biogenic silver nanoparticles (AgNPs) against human breast cancer (MCF-7) cells towards the development of anticancer agent. Biogenic AgNPs were achieved by employing Sesbania grandiflora leaf extract as a novel reducing agent. It was well characterized by FESEM, EDAX and spectral studies showed spherical shaped nanoparticles in the size of 22 nm in slightly agglomerated form. It was surprising that biogenic AgNPs showed cytotoxic effect against MCF-7 cell lines were confirmed by MTT, AO-EB, Hochest and COMET assays. There was an immediate induction of cellular damage in terms of loss of cell membrane integrity, oxidative stress and apoptosis were found in the cell which treated with AgNPs. This may be a first report on anti-MCF-7 property of biogenic AgNPs in the fourth generation of nanoparticles research. It is necessary to study the formulation and clinical trials to establish the nano drug to treat cancer cells. PMID:23434696

Jeyaraj, M; Sathishkumar, G; Sivanandhan, G; MubarakAli, D; Rajesh, M; Arun, R; Kapildev, G; Manickavasagam, M; Thajuddin, N; Premkumar, K; Ganapathi, A

2013-06-01

347

Colloidal silver nanoparticles/rhamnolipid (SNPRL) composite as novel chemotactic antibacterial agent.  

PubMed

The antibacterial activity of silver nanoparticles and rhamnolipid are well known individually. In the present research, antibacterial and chemotactic activity due to colloidal silver nanoparticles (SNP), rhamnolipid (RL) and silver nanoparticles/rhamnolipid composite (SNPRL) were evaluated using Staphylococcus aureus (MTCC3160), Escherichia coli (MTCC40), Pseudomonas aeruginosa (MTCC8163) and Bacillus subtilis (MTCC441) as test strains. Further, the SNPRL nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The observation clearly indicates that SNPRL shows prominent antibacterial and chemotactic activity in comparison to all of its individual precursor components. PMID:23850558

Bharali, P; Saikia, J P; Paul, S; Konwar, B K

2013-10-01

348

The investigation of oxidized silver nanoparticles prepared by thermal evaporation and radio-frequency sputtering of metallic silver under oxygen  

NASA Astrophysics Data System (ADS)

The investigation of oxidized silver nanoparticles by the photoemission (XPS, UPS) and HRTEM methods was performed. The nanoparticles of oxidized silver were obtained in the vacuum chamber by two methods of synthesis: thermal evaporation of silver nanoparticles followed by transferring in convective gas flow and sputtering of oxidized clusters under the action of plasma. Both methods indicated that oxygen interaction with silver nanoparticles depends strongly on its size. It was shown that the chemical bonding of oxygen species stabilized on small particles differs from the oxygen species adsorbed on bulk silver surfaces (monocrystals, foils and large particles). The low charged oxygen with molecular type of bonding stabilizes on particles of size approximately 5 nm and smaller. Increasing particle size leads to the dissociation of molecular oxygen species and the formation of strongly charged oxygen composed of oxide nanoparticles like Ag2O or AgO type. The presence of extended defects in the microdomain large nanoparticles facilitates the formation of Ag2O or AgO layers covering metallic nanosilver.

Kibis, L. S.; Stadnichenko, A. I.; Pajetnov, E. M.; Koscheev, S. V.; Zaykovskii, V. I.; Boronin, A. I.

2010-11-01

349

Sequential studies of silver released from silver nanoparticles in aqueous media simulating sweat, laundry detergent solutions and surface water.  

PubMed

From an increased use of silver nanoparticles (Ag NPs) as an antibacterial in consumer products follows a need to assess the environmental interaction and fate of their possible dispersion and release of silver. This study aims to elucidate an exposure scenario of the Ag NPs potentially released from, for example, impregnated clothing by assessing the release of silver and changes in particle properties in sequential contact with synthetic sweat, laundry detergent solutions, and freshwater, simulating a possible transport path through different aquatic media. The release of ionic silver is addressed from a water chemical perspective, compared with important particle and surface characteristics. Released amounts of silver in the sequential exposures were significantly lower, approximately a factor of 2, than the sum of each separate exposure. Particle characteristics such as speciation (both of Ag ionic species and at the Ag NP surface) influenced the release of soluble silver species present on the surface, thereby increasing the total silver release in the separate exposures compared with sequential immersions. The particle stability had no drastic impact on the silver release as most of the Ag NPs were unstable in solution. The silver release was also influenced by a lower pH (increased release of silver), and cotransported zeolites (reduced silver in solution). PMID:24892700

Hedberg, Jonas; Skoglund, Sara; Karlsson, Maria-Elisa; Wold, Susanna; Odnevall Wallinder, Inger; Hedberg, Yolanda

2014-07-01

350

Control of Colloid Surface Chemistry through Matrix Confinement: Facile Preparation of Stable Antibody Functionalized Silver Nanoparticles  

PubMed Central

Here we describe a simple yet efficient gel matrix assisted preparation method which improves synthetic control over the interface between inorganic nanomaterials and biopolymers and yields stable biofunctionalized silver nanoparticles. Covalent functionalization of the noble metal surface is aided by the confinement of polyethylene glycol acetate functionalized silver nanoparticles in thin slabs of a 1% agarose gel. The gel confined nanoparticles can be transferred between reaction and washing media simply by immersing the gel slab in the solution of interest. The agarose matrix retains nanoparticles but is swiftly penetrated by the antibodies of interest. The antibodies are covalently anchored to the nanoparticles using conventional crosslinking strategies, and the resulting antibody functionalized nanoparticles are recovered from the gel through electroelution. We demonstrate the efficacy of this nanoparticle functionalization approach by labeling specific receptors on cellular surfaces with functionalized silver nanoparticles that are stable under physiological conditions.

Skewis, Lynell R.; Reinhard, Bjorn M.

2010-01-01

351

Genotoxicity of copper oxide and silver nanoparticles in the mussel Mytilus galloprovincialis.  

PubMed

Though there is some information on cytotoxicity of copper nanoparticles and silver nanoparticles on human cell lines, there is no information on their genotoxic and cytotoxic behaviour in bivalve molluscs. The aim of this study was to investigate the genotoxic impact of copper oxide and silver nanoparticles using mussels Mytilus galloprovincialis. Mussels were exposed to 10 ?g L?¹ of CuO nanoparticles and Cu²? and Ag nanoparticles and Ag? for 15 days to assess genotoxic effects in hemocytes using the comet assay. The results obtained indicated that copper and silver forms (nanoparticles and ionic) induced DNA damage in hemolymph cells and a time-response effect was evident when compared to unexposed mussels. Ionic forms presented higher genotoxicity than nanoparticles, suggesting different mechanisms of action that may be mediated through oxidative stress. DNA strand breaks proved to be a useful biomarker of exposure to genotoxic effects of CuO and Ag nanoparticles in marine molluscs. PMID:23294529

Gomes, Tânia; Araújo, Olinda; Pereira, Rita; Almeida, Ana C; Cravo, Alexandra; Bebianno, Maria João

2013-03-01

352

Spectroscopic, microscopic and catalytic properties of silver nanoparticles synthesized using Saraca indica flower  

NASA Astrophysics Data System (ADS)

The bioprospective field is dynamic area of research in the recent years. The present article reports a green synthetic route for the production of highly stable, bio-inspired silver nanoparticles using dried Saraca indica flower. The method is facile, cost effective, simple and reproducible. The reduction of silver ions and the formation of silver nanoparticles has been monitored using UV-visible spectroscopy. The TEM, SAED and XRD result reveal that the silver nanoparticles are crystalline in nature. FTIR spectra are used to identify the biomolecules that bind on the surface of silver nanoparticles, which increased the stability of the particles. S. indica flower extract plays its role as an excellent reducing agent of silver ions and the biosynthesized silver nanoparticles are safer to environment. Also the size dependent catalytic activity of silver nanoparticles in the reduction of cationic dye, Methylene blue by NaBH4 is studied by UV-visible spectroscopy. The efficiency of synthesized nanoparticles as an excellent catalyst is proved by the reduction of Methylene blue which is confirmed by the decrease in the absorbance with time and is attributed to electron relay effect.

Vidhu, V. K.; Philip, Daizy

2014-01-01

353

Photoemission Electron Microscopy of a Plasmonic Silver Nanoparticle Trimer  

SciTech Connect

We present a combined experimental and theoretical study to investigate the spatial distribution of photoelectrons emitted from core-shell silver (Ag) nanoparticles. We use two-photon photoemission microscopy (2P-PEEM) to spatially resolve electron emission from a trimeric core-shell aggregate of triangular symmetry. Finite difference time domain (FDTD) simulations are performed to model the intensity distributions of the electromagnetic near-fields resulting from femtosecond (fs) laser excitation of localized surface plasmon oscillations in the triangular core-shell structure. We demonstrate that the predicted FDTD near-field intensity distribution reproduces the 2P-PEEM photoemission pattern.

Peppernick, Samuel J.; Joly, Alan G.; Beck, Kenneth M.; Hess, Wayne P.; Wang, Jinyong; Wang, Yi-Chung; Wei, Wei

2013-07-01

354

Biosynthesis of silver and gold nanoparticles by novel sundried Cinnamomum camphora leaf  

NASA Astrophysics Data System (ADS)

The synthesis of nanocrystals is in the limelight in modern nanotechnology. Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Not only could silver nanoparticles ranging from 55 to 80 nm in size be fabricated, but also triangular or spherical shaped gold nanoparticles could be easily modulated by reacting the novel sundried biomass of Cinnamomum camphora leaf with aqueous silver or gold precursors at ambient temperature. The marked difference of shape control between gold and silver nanoparticles was attributed to the comparative advantage of protective biomolecules and reductive biomolecules. The polyol components and the water-soluble heterocyclic components were mainly responsible for the reduction of silver ions or chloroaurate ions and the stabilization of the nanoparticles, respectively. The sundried leaf in this work was very suitable for simple synthesis of nanoparticles.

Huang, Jiale; Li, Qingbiao; Sun, Daohua; Lu, Yinghua; Su, Yuanbo; Yang, Xin; Wang, Huixuan; Wang, Yuanpeng; Shao, Wenyao; He, Ning; Hong, Jinqing; Chen, Cuixue

2007-03-01

355

Procedures for the synthesis and capping of metal nanoparticles.  

PubMed

The increasing impact of metallic nanoparticles in life sciences has stimulated the development of new techniques and multiple improvements of the existing methods of manufacturing nanoparticles with tailored properties. Nanoparticles can be synthesized through a variety of physical and chemical methods. The choice of preparation procedure will depend on the physical and chemical characteristics required on the final product, such as size, dispersion, chemical miscibility, optical properties, among others. Here we review basic practical procedures used for the preparation of protected and unprotected metallic nanoparticles and describe a number of experimental procedures based on colloidal chemistry methods. These include gold nanoparticle synthesis by reduction with trisodium citrate, ascorbic acid, or sugars in aqueous phase; nanoparticle passivation with alkanethiols, cetyltrimethylammonium bromide, or bovin serum albumin. We also describe microwave-assisted synthesis, nanoparticle synthesis in ethylene glycol, template-assisted synthesis with dendrimers and briefly describe how to control nanoparticle shape (star-shaped and branched nanoparticles). PMID:22791420

Gutiérrez-Wing, Claudia; Velázquez-Salazar, J Jesús; José-Yacamán, Miguel

2012-01-01

356

Silver nanoparticle aided self-healing of polyelectrolyte multilayers.  

PubMed

Self-healing is the ability of a material to repair mechanical damage. The lifetime of a coating or film might be lengthened with this capacity. Water enabled self-healing of polyelectrolyte multilayers has been reported, using systems that grow via the interdiffusion of polyelectrolyte chains. Due to high mobility of the polyelectrolyte chains within the assembly, it is possible for lateral diffusion to heal over scratches. The influence of metal ions and nanoparticles on this property has, however, not been previously studied. Here we demonstrate that the incorporation of silver nanoparticles reduced in situ within the branched poly(ethyleneimine)-poly(acrylic acid) polyelectrolyte multilayer structure speeds the ability of the multilayer assembly to self-heal. This enhancement of property seems to not be due to changes in mechanical properties but rather in enhanced affinity to water and plasticization that enables the film to better swell. PMID:24728290

Huang, Xiayun; Bolen, Matthew J; Zacharia, Nicole S

2014-06-14

357

Mechanistic insights into interaction of humic acid with silver nanoparticles.  

PubMed

Humic acid (HA) is one of the major components of the natural organic matter present in the environment that alters the fate and behavior of silver nanoparticles (Ag NPs). Transformation of Ag NPs happens upon interaction with HA, thereby, changing both physical and chemical properties. Fluorescence spectroscopy and scanning electron microscopy (SEM) were used to analyze the interaction of Ag NPs with HA. In pH and time-dependent studies, the near field electro dynamical environment of Ag NPs influenced the fluorescence of HA, indicated by fluorescence enhancement. SEM revealed not only morphological changes, but also significant reduction in size of Ag NPs after interaction with HA. Based on these studies, a probable mechanism was proposed for the interaction of HA with Ag NPs, suggesting the possible transformation that these nanoparticles can undergo in the environment. PMID:23801156

Manoharan, Vijayan; Ravindran, Aswathy; Anjali, C H

2014-01-01

358

Controlled synthesis of PbS-Au nanostar-nanoparticle heterodimers and cap-like Au nanoparticles  

NASA Astrophysics Data System (ADS)

Uniform PbS-Au nanostar-nanoparticle heterodimers consisting of one Au nanoparticle grown on one horn of a well-defined six-horn PbS nanostar were prepared using the PbS nanostars as growth substrates for the selective deposition of Au nanoparticles. The size of the Au nanoparticles on the horns of the PbS nanostars could be readily adjusted by changing the PbS concentration for the deposition of Au nanoparticles. An optimum cetyltrimethylammonium bromide concentration and temperature were essential for the selective deposition of uniform Au nanoparticles on single horns of the PbS nanostars. Unusual PbS-Au nanoframe-nanoparticle heterodimers were obtained by etching the PbS-Au nanostar-nanoparticle heterodimers with oxalic acid while novel cap-like Au nanoparticles were obtained by etching with hydrochloric acid. The obtained heterodimeric nanostructures and cap-like nanoparticles are promising candidates for anisotropic nanoscale building blocks for the controllable assembly of useful, complex architectures.

Zhao, Nana; Li, Lianshan; Huang, Teng; Qi, Limin

2010-11-01

359

Correlation of biomarkers and histological responses in manufactured silver nanoparticle toxicity  

Microsoft Academic Search

Today nanosciences are experiencing massive investment worldwide although research on toxicological aspect of these nano-sized\\u000a particles has just begun and to date, no clear guidelines exist to quantify the effects. In the present study, we focus on\\u000a silver nanoparticles, which represent one of the most widely investigated nanoparticles. The present data indicate that silver\\u000a nanoparticles seem to cross the cellular

Eunjoo Kim; Jin-Hee Maeng; Don Haeng Lee; Joon Mee Kim

2009-01-01

360

A novel method for synthesis of colloidal silver nanoparticles by arc discharge in liquid  

Microsoft Academic Search

This paper presents a novel, inexpensive and one-step approach for synthesis of silver nanoparticles (Ag NPs) using arc discharge between titanium electrodes in AgNO3 solution. The resulting nanoparticles were characterized using UV–Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Silver nanoparticles of 18 nm diameter were formed during reduction of AgNO3 in plasma discharge zone. Optical absorption spectroscopy

Ali Akbar Ashkarran

2010-01-01

361

Preparation and optical properties of colloidal silver nanoparticles at a high Ag + concentration  

Microsoft Academic Search

We have prepared colloidal silver nanoparticles by reducing a high molar concentration of AgNO3 (up to 0.735 M) with glycerol in the presence of m-phenylenediamine. These silver nanoparticles had anisotropic shapes, including truncated rectangles, truncated triangles, and spheroid-type particles. The UV–Vis spectra of these nanoparticle systems display two distinct plasmon modes and a shoulder that correspond to the in-plane dipole,

M. Habib Ullah; Kim Il; Chang-Sik Ha

2006-01-01

362

Influence of silver nanoparticles on neurons and blood-brain barrier via subcutaneous injection in rats  

Microsoft Academic Search

Nanosilver has been widely used in medical biology; however, the distribution and interaction of nanosilver with cells is still unclear. There have been some reports demonstrating that nanoparticles can cross the blood-brain barrier (BBB). The present study investigated the accumulation of silver nanoparticles in the brain, and the effects of silver nanoparticles on BBB. Nanosilver and microsilver (62.8mg\\/kg) particles were

Jinglong Tang; Ling Xiong; Shuo Wang; Jianyu Wang; Li Liu; Jiage Li; Ziyi Wan; Tingfei Xi

2008-01-01

363

Micro-Raman Spectroscopy of Silver Nanoparticle Induced Stress on Optically-Trapped Stem Cells  

Microsoft Academic Search

We report here results of a single-cell Raman spectroscopy study of stress effects induced by silver nanoparticles in human mesenchymal stem cells (hMSCs). A high-sensitivity, high-resolution Raman Tweezers set-up has been used to monitor nanoparticle-induced biochemical changes in optically-trapped single cells. Our micro-Raman spectroscopic study reveals that hMSCs treated with silver nanoparticles undergo oxidative stress at doping levels in excess

Aseefhali Bankapur; R. Sagar Krishnamurthy; Elsa Zachariah; Chidangil Santhosh; Basavaraj Chougule; Bhavishna Praveen; Manna Valiathan; Deepak Mathur

2012-01-01

364

The anodic stripping voltammetry of nanoparticles: electrochemical evidence for the surface agglomeration of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Analytical expressions for the anodic stripping voltammetry of metallic nanoparticles from an electrode are provided. First, for reversible electron transfer, two limits are studied: that of diffusionally independent nanoparticles and the regime where the diffusion layers originating from each particle overlap strongly. Second, an analytical expression for the voltammetric response under conditions of irreversible electron transfer kinetics is also derived. These equations demonstrate how the peak potential for the stripping process is expected to occur at values negative of the formal potential for the redox process in which the surface immobilised nanoparticles are oxidised to the corresponding metal cation in the solution phase. This work is further developed by considering the surface energies of the nanoparticles and its effect on the formal potential for the oxidation. The change in the formal potential is modelled in accordance with the equations provided by Plieth [J. Phys. Chem., 1982, 86, 3166-3170]. The new analytical expressions are used to investigate the stripping of silver nanoparticles from a glassy carbon electrode. The relative invariance of the stripping peak potential at low surface coverages of silver is shown to be directly related to the surface agglomeration of the nanoparticles.

Toh, Her Shuang; Batchelor-McAuley, Christopher; Tschulik, Kristina; Uhlemann, Margitta; Crossley, Alison; Compton, Richard G.

2013-05-01

365

Monolayers of silver nanoparticles decrease photobleaching: application to muscle myofibrils.  

PubMed

Studying single molecules in a cell has the essential advantage that kinetic information is not averaged out. However, since fluorescence is faint, such studies require that the sample be illuminated with the intense light beam. This causes photodamage of labeled proteins and rapid photobleaching of the fluorophores. Here, we show that a substantial reduction of these types of photodamage can be achieved by imaging samples on coverslips coated with monolayers of silver nanoparticles. The mechanism responsible for this effect is the interaction of localized surface plasmon polaritons excited in the metallic nanoparticles with the transition dipoles of fluorophores of a sample. This leads to a significant enhancement of fluorescence and a decrease of fluorescence lifetime of a fluorophore. Enhancement of fluorescence leads to the reduction of photodamage, because the sample can be illuminated with a dim light, and decrease of fluorescence lifetime leads to reduction of photobleaching because the fluorophore spends less time in the excited state, where it is susceptible to oxygen attack. Fluorescence enhancement and reduction of photobleaching on rough metallic surfaces are usually accompanied by a loss of optical resolution due to refraction of light by particles. In the case of monolayers of silver nanoparticles, however, the surface is smooth and glossy. The fluorescence enhancement and the reduction of photobleaching are achieved without sacrificing the optical resolution of a microscope. Skeletal muscle myofibrils were used as an example, because they contain submicron structures conveniently used to define optical resolution. Small nanoparticles (diameter approximately 60 nm) did not cause loss of optical resolution, and they enhanced fluorescence approximately 500-fold and caused the appearance of a major picosecond component of lifetime decay. As a result, the sample photobleached approximately 20-fold more slowly than the sample on glass coverslips. PMID:18556759

Muthu, P; Calander, N; Gryczynski, I; Gryczynski, Z; Talent, J M; Shtoyko, T; Akopova, I; Borejdo, J

2008-10-01

366

Studies on the chemical synthesis and characterization of lead oxide nanoparticles with different organic capping agents  

SciTech Connect

Lead oxide (PbO) nanoparticles were chemically synthesized using Lead (II) acetate as precursor. The effects of organic capping agents such as Oleic acid, Ethylene Diamine Tetra Acetic acid (EDTA) and Cetryl Tri Methyl Butoxide (CTAB) on the size and morphology of the nanoparticles were studied. Characterization techniques such as X-ray diffraction (XRD), Fourier Transform-Infrared spectroscopy (FT-IR), Photoluminescence (PL) Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM) were used to analyse the prepared nanoparticles for their physical, structural and optical properties. The characterization studies reveal that the synthesized PbO nanoparticles had well defined crystalline structure and sizes in the range of 25 nm to 36 nm for capping agents used and 40 nm for pure PbO nanoparticles.

Arulmozhi, K. T., E-mail: arulsheelphy@gmail.com [Physics Wing (DDE), Annamalai University, Tamil Nadu, India - 608 002 (India); Mythili, N. [Department of Physics, Annamalai University, Tamil Nadu, India - 608 002 (India)] [Department of Physics, Annamalai University, Tamil Nadu, India - 608 002 (India)

2013-12-15

367

Studies on the chemical synthesis and characterization of lead oxide nanoparticles with different organic capping agents  

NASA Astrophysics Data System (ADS)

Lead oxide (PbO) nanoparticles were chemically synthesized using Lead (II) acetate as precursor. The effects of organic capping agents such as Oleic acid, Ethylene Diamine Tetra Acetic acid (EDTA) and Cetryl Tri Methyl Butoxide (CTAB) on the size and morphology of the nanoparticles were studied. Characterization techniques such as X-ray diffraction (XRD), Fourier Transform-Infrared spectroscopy (FT-IR), Photoluminescence (PL) Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM) were used to analyse the prepared nanoparticles for their physical, structural and optical properties. The characterization studies reveal that the synthesized PbO nanoparticles had well defined crystalline structure and sizes in the range of 25 nm to 36 nm for capping agents used and 40 nm for pure PbO nanoparticles.

Arulmozhi, K. T.; Mythili, N.

2013-12-01

368

Improving of enzyme immunoassay for detection and quantification of the target molecules using silver nanoparticles  

NASA Astrophysics Data System (ADS)

Modern routine enzyme immunoassays for detection and quantification of biomolecules have several disadvantages such as high cost, insufficient sensitivity, complexity and long-term execution. The surface plasmon resonance of silver nanoparticles gives reasons of creating new in the basis of simple, highly sensitive and low cost colorimetric assays that can be applied to the detection of small molecules, DNA, proteins and pollutants. The main aim of the study was the improving of enzyme immunoassay for detection and quantification of the target molecules using silver nanoparticles. For this purpose we developed method for synthesis of silver nanoparticles with hyaluronic acid and studied possibility of use these nanoparticles in direct determination of target molecules concentration (in particular proteins) and for improving of enzyme immunoassay. As model we used conventional enzyme immunoassays for determination of progesterone and estradiol concentration. We obtained the possibility to produce silver nanoparticles with hyaluronan homogeneous in size between 10 and 12 nm, soluble and stable in water during long term of storage using modified procedure of silver nanoparticles synthesis. New method allows to obtain silver nanoparticles with strong optical properties at the higher concentrations - 60-90 ?g/ml with the peak of absorbance at the wavelength 400 nm. Therefore surface plasmon resonance of silver nanoparticles with hyaluronan and ultraviolet-visible spectroscopy provide an opportunity for rapid determination of target molecules concentration (especial protein). We used silver nanoparticles as enzyme carriers and signal enhancers. Our preliminary data show that silver nanoparticles increased absorbance of samples that allows improving upper limit of determination of estradiol and progesterone concentration.

Syrvatka, Vasyl J.; Slyvchuk, Yurij I.; Rozgoni, Ivan I.; Gevkan, Ivan I.; Overchuk, Marta O.

2014-02-01

369

Redox decomposition of silver citrate complex in nanoscale confinement: an unusual mechanism of formation and growth of silver nanoparticles.  

PubMed

We demonstrate for the first time the intrinsic role of nanoconfinement in facilitating the chemical reduction of metal ion precursors with a suitable reductant for the synthesis of metal nanoparticles, when the identical reaction does not occur in bulk solution. Taking the case of citrate reduction of silver ions under the unusual condition of [citrate]/[Ag(+)] ? 1, it has been observed that the silver citrate complex, stable in bulk solution, decomposes readily in confined nanodomains of charged and neutral matrices (ion-exchange film and porous polystyrene beads), leading to the formation of silver nanoparticles. The evolution of growth of silver nanoparticles in the ion-exchange films has been studied using a combination of (110m)Ag radiotracer, small-angle X-ray scattering (SAXS) experiments, and transmission electron microscopy (TEM). It has been observed that the nanoconfined redox decomposition of silver citrate complex is responsible for the formation of Ag seeds, which thereafter catalyze oxidation of citrate and act as electron sink for subsequent reduction of silver ions. Because of these parallel processes, the particle sizes are in the bimodal distribution at some stages of the reaction. A continuous seeding with parallel growth mechanism has been revealed. Based on the SAXS data and radiotracer kinetics, the growth mechanism has been elucidated as a combination of continuous autoreduction of silver ions on the nanoparticle surfaces and a sudden coalescence of nanoparticles at a critical number density. However, for a fixed period of reduction, the size, size distribution, and number density of thus-formed Ag nanoparticles have been found to be dependent on physical architecture and chemical composition of the matrix. PMID:24533743

Patra, Sabyasachi; Pandey, Ashok K; Sen, Debasis; Ramagiri, Shobha V; Bellare, Jayesh R; Mazumder, S; Goswami, A

2014-03-11

370

Silver-doped calcium phosphate nanoparticles: synthesis, characterization, and toxic effects toward mammalian and prokaryotic cells.  

PubMed

Spherical silver-doped calcium phosphate nanoparticles were synthesized in a co-precipitation route from calcium nitrate/silver nitrate and ammonium phosphate in a continuous process and colloidally stabilized by carboxymethyl cellulose. Nanoparticles with 0.39 wt% silver content and a diameter of about 50-60 nm were obtained. The toxic effects toward mammalian and prokaryotic cells were determined by viability tests and determination of the minimal inhibitory and minimal bactericidal concentrations (MIC and MBC). Three mammalian cells lines, i.e. human mesenchymal stem cells (hMSC) and blood peripheral mononuclear cells (PBMC, monocytes and T-lymphocytes), and two prokaryotic strains, i.e. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used. Silver-doped calcium phosphate nanoparticles and silver acetate showed similar effect toward mammalian and prokaryotic cells with toxic silver concentrations in the range of 1-3 ?g mL(-1). PMID:23107950

Peetsch, Alexander; Greulich, Christina; Braun, Dieter; Stroetges, Christian; Rehage, Heinz; Siebers, Bettina; Köller, Manfred; Epple, Matthias

2013-02-01

371

Sorption of silver nanoparticles to environmental and model surfaces.  

PubMed

The fate of engineered nanoparticles in environmental systems is controlled by changes in colloidal stability and their interaction with different environmental surfaces. Little is known about nanoparticle-surface interactions on the basis of sorption isotherms under quasi-equilibrium conditions, although sorption isotherms are a valuable means of studying sorbate-sorbent interactions. We tested the extent to which the sorption of engineered silver nanoparticles (nAg) from stable and unstable suspensions to model (sorbents with specific chemical functional groups) and environmental (plant leaves and sand) surfaces can be described by classical sorption isotherms. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) qualitative and quantitative analyses were also used to assess the morphology and nanomechanical parameters of the covered surfaces. The sorption of nAg from stable suspensions was nonlinear and best described by the Langmuir isotherm. Langmuir coefficients varied with sorbent surface chemistry. For nAg sorption from an unstable suspension, the sorption isotherms did not follow any classical sorption models, suggesting interplay between aggregation and sorption. The validity of the Langmuir isotherm suggests monolayer sorption, which can be explained by the blocking effect due to electrostatic repulsion of individual nanoparticles. In unstable suspensions, aggregates are instead formed in suspension and then sorbed, formed on the surface itself, or formed in both ways. PMID:23621856

Abraham, Priya M; Barnikol, Sandra; Baumann, Thomas; Kuehn, Melanie; Ivleva, Natalia P; Schaumann, Gabriele E

2013-05-21

372

Transport of bare and capped zinc oxide nanoparticles is dependent on porous medium composition.  

PubMed

Zinc oxide (ZnO) nanoparticles are one of the most frequently used nanoparticles in industry and hence are likely to be introduced to the groundwater environment. The mobility of these nanoparticles in different aquifer materials has not been assessed. While some studies have been published on the transport of ZnO nanoparticles in individual porous media, these studies do not generally account for varying porous medium composition both within and between aquifers. As a first step towards understanding the impact of this variability, this paper compares the transport of bare ZnO nanoparticles (bZnO-NPs) and capped ZnO nanoparticles, coated with tri-aminopropyltriethoxysilane (cZnO-NPs), in saturated columns packed with glass beads, fine grained sand and fine grained calcite, at near-neutral pH and groundwater salinity levels. With the exception of cZnO-NPs in sand columns, ZnO nanoparticles are highly immobile in all three types of studied porous media, with most retention taking place near the column inlet. Results are in general agreement with DLVO theory, and the deviation in experiments with cZnO-NPs flowing through columns packed with sand is linked to variability in zeta potential of the capped nanoparticles and sand grains. Therefore, differences in surface charge of nanoparticles and porous media are demonstrated to be key drivers in nanoparticle transport. PMID:24796515

Kurlanda-Witek, H; Ngwenya, B T; Butler, I B

2014-07-01

373

Transport of bare and capped zinc oxide nanoparticles is dependent on porous medium composition  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) nanoparticles are one of the most frequently used nanoparticles in industry and hence are likely to be introduced to the groundwater environment. The mobility of these nanoparticles in different aquifer materials has not been assessed. While some studies have been published on the transport of ZnO nanoparticles in individual porous media, these studies do not generally account for varying porous medium composition both within and between aquifers. As a first step towards understanding the impact of this variability, this paper compares the transport of bare ZnO nanoparticles (bZnO-NPs) and capped ZnO nanoparticles, coated with tri-aminopropyltriethoxysilane (cZnO-NPs), in saturated columns packed with glass beads, fine grained sand and fine grained calcite, at near-neutral pH and groundwater salinity levels. With the exception of cZnO-NPs in sand columns, ZnO nanoparticles are highly immobile in all three types of studied porous media, with most retention taking place near the column inlet. Results are in general agreement with DLVO theory, and the deviation in experiments with cZnO-NPs flowing through columns packed with sand is linked to variability in zeta potential of the capped nanoparticles and sand grains. Therefore, differences in surface charge of nanoparticles and porous media are demonstrated to be key drivers in nanoparticle transport.

Kurlanda-Witek, H.; Ngwenya, B. T.; Butler, I. B.

2014-07-01

374

A novel photosynthesis of carboxymethyl starch-stabilized silver nanoparticles.  

PubMed

The water soluble photoinitiator (PI) 4-(trimethyl ammonium methyl) benzophenone chloride is used for the first time in the synthesis of silver nanoparticles (AgNPs). A new green synthesis method involves using PI/UV system, carboxymethyl starch (CMS), silver nitrate, and water. A mechanism of the reduction of silver ions to AgNPs by PI/UV system as well as by the newly born aldehydic groups was proposed. The synthesis process was assessed by UV-vis spectra and TEM of AgNPs colloidal solution. The highest absorbance was obtained using CMS, PI and AgNO3 concentrations of 10 g/L, 1 g/L, and 1 g/L, respectively; 40 °C; 60 min; pH 7; and a material : liquor ratio 1 : 20. AgNPs so-obtained were stable in aqueous solution over a period of three weeks at room temperature (~25 °C) and have round shape morphology. The sizes of synthesized AgNPs were in the range of 1-21 nm and the highest counts % of these particles were for particles of 6-10 and 1-3 nm, respectively. PMID:24672325

El-Sheikh, M A

2014-01-01

375

A Novel Photosynthesis of Carboxymethyl Starch-Stabilized Silver Nanoparticles  

PubMed Central

The water soluble photoinitiator (PI) 4-(trimethyl ammonium methyl) benzophenone chloride is used for the first time in the synthesis of silver nanoparticles (AgNPs). A new green synthesis method involves using PI/UV system, carboxymethyl starch (CMS), silver nitrate, and water. A mechanism of the reduction of silver ions to AgNPs by PI/UV system as well as by the newly born aldehydic groups was proposed. The synthesis process was assessed by UV-vis spectra and TEM of AgNPs colloidal solution. The highest absorbance was obtained using CMS, PI and AgNO3 concentrations of 10?g/L, 1?g/L, and 1?g/L, respectively; 40°C; 60?min; pH 7; and a material?:?liquor ratio 1?:?20. AgNPs so-obtained were stable in aqueous solution over a period of three weeks at room temperature (~25°C) and have round shape morphology. The sizes of synthesized AgNPs were in the range of 1–21?nm and the highest counts % of these particles were for particles of 6–10 and 1–3?nm, respectively.

El-Sheikh, M. A.

2014-01-01

376

Accumulation of silver nanoparticles by cultured primary brain astrocytes  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (AgNP) are components of various food industry products and are frequently used for medical equipment and materials. Although such particles enter the vertebrate brain, little is known on their biocompatibility for brain cells. To study the consequences of an AgNP exposure of brain cells we have treated astrocyte-rich primary cultures with polyvinylpyrrolidone (PVP)-coated AgNP. The incubation of cultured astrocytes with micromolar concentrations of AgNP for up to 24 h resulted in a time- and concentration-dependent accumulation of silver, but did not compromise the cell viability nor lower the cellular glutathione content. In contrast, the incubation of astrocytes for 4 h with identical amounts of silver as AgNO3 already severely compromised the cell viability and completely deprived the cells of glutathione. The accumulation of AgNP by astrocytes was proportional to the concentration of AgNP applied and significantly lowered by about 30% in the presence of the endocytosis inhibitors chloroquine or amiloride. Incubation at 4 °C reduced the accumulation of AgNP by 80% compared to the values obtained for cells that had been exposed to AgNP at 37 °C. These data demonstrate that viable cultured brain astrocytes efficiently accumulate PVP-coated AgNP in a temperature-dependent process that most likely involves endocytotic pathways.

Luther, Eva M.; Koehler, Yvonne; Diendorf, Joerg; Epple, Matthias; Dringen, Ralf

2011-09-01

377

Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles  

PubMed Central

We used an aqueous leaf extract of Memecylon edule (Melastomataceae) to synthesize silver and gold nanoparticles. To our knowledge, this is the first report where M. edule leaf broth was found to be a suitable plant source for the green synthesis of silver and gold nanoparticles. On treatment of aqueous solutions of silver nitrate and chloroauric acid with M. edule leaf extract, stable silver and gold nanoparticles were rapidly formed. The gold nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and Fourier transform infra-red spectroscopy (FTIR). The kinetics of reduction of aqueous silver and gold ions during reaction with the M. edule leaf broth were easily analyzed by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to M. edule leaf broth, were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. TEM analysis of gold nanoparticles showed formation of triangular, circular, and hexagonal shapes in the size range 10–45 nm. The resulting silver nanoparticles were predominantly square with uniform size range 50–90 nm. EDAX results confirmed the presence of triangular nanoparticles in the adsorption peak of 2.30 keV. Further FTIR analysis was also done to identify the functional groups in silver and gold nanoparticles. The characterized nanoparticles of M. edule have potential for various medical and industrial applications. Saponin presence in aqueous extract of M. edule is responsible for the mass production of silver and gold nanoparticles.

Elavazhagan, Tamizhamudu; Arunachalam, Kantha D

2011-01-01

378

Sulfidation of silver nanoparticles: natural antidote to their toxicity.  

PubMed

Nanomaterials are highly dynamic in biological and environmental media. A critical need for advancing environmental health and safety research for nanomaterials is to identify physical and chemical transformations that affect the nanomaterial properties and their toxicity. Silver nanoparticles, one of the most toxic and well-studied nanomaterials, readily react with sulfide to form Ag(0)/Ag2S core-shell particles. Here, we show that sulfidation decreased silver nanoparticle toxicity to four diverse types of aquatic and terrestrial eukaryotic organisms (Danio rerio (zebrafish), Fundulus heteroclitus (killifish), Caenorhabditis elegans (nematode worm), and the aquatic plant Lemna minuta (least duckweed)). Toxicity reduction, which was dramatic in killifish and duckweed even for low extents of sulfidation (about 2 mol % S), is primarily associated with a decrease in Ag(+) concentration after sulfidation due to the lower solubility of Ag2S relative to elemental Ag (Ag(0)). These results suggest that even partial sulfidation of AgNP will decrease the toxicity of AgNPs relative to their pristine counterparts. We also show that, for a given organism, the presence of chloride in the exposure media strongly affects the toxicity results by affecting Ag speciation. These results highlight the need to consider environmental transformations of NPs in assessing their toxicity to accurately portray their potential environmental risks. PMID:24180218

Levard, Clement; Hotze, Ernest M; Colman, Benjamin P; Dale, Amy L; Truong, Lisa; Yang, X Y; Bone, Audrey J; Brown, Gordon E; Tanguay, Robert L; Di Giulio, Richard T; Bernhardt, Emily S; Meyer, Joel N; Wiesner, Mark R; Lowry, Gregory V

2013-12-01

379

Synthesis of silica nanoparticles covered with silver beads.  

PubMed

Procedures for producing silica nanoparticles suitable for further amino functionalization and subsequent decoration with silica beads were investigated in a comparative way. Several methods, one based on tetrapropylammonium hydroxide, the classical Stöber synthesis, and two with amino acids (either lysine or arginine) as catalysts were employed and followed by means of DLS, SAXS, and TEM. The amino acid methods proved to be by far the most satisfactory ones, yielding highly spherical and monodisperse nanoparticles with a tunable size range of 15-100 nm. The surface of the particles could be functionalized with propylamine, which enabled to obtain positive surface charge at low pH and to tune the zeta potential by the pH in the range of +/- 40 mV. Finally, the modified particles were used to reduce silver (I) ions at high pH, leading to the formation of very small silver beads covering the silica surface and yielding a nanocomposite with a "raspberry" structure. Interestingly, this could be achieved without using any complementary reducing agent besides the particles themselves, thereby opening a very simple path to the formation of composite metal containing colloidal systems. PMID:24245142

Joksimovic, Rastko; Altin, Burcu; Mehta, Surinder K; Gradzielski, Michael

2013-10-01

380

Antibacterial activity of silver nanoparticles: sensitivity of different Salmonella serovars  

PubMed Central

Salmonella spp. is one of the main causes of foodborne illnesses in humans worldwide. Consequently, great interest exists in reducing its impact on human health by lowering its prevalence in the food chain. Antimicrobial formulations in the form of nanoparticles exert bactericidal action due to their enhanced reactivity resultant from their high surface/volume ratio. Silver nanoparticles (AgNPs) are known to be highly toxic to Gram-negative and Gram-positive microorganisms, including multidrug resistant bacteria. However, few data concerning their success against different Salmonella serovars are available. Aims of the present study were to test the antimicrobial effectiveness of AgNPs, against Salmonella Enteritidis, Hadar, and Senftenberg, and to investigate the causes of their different survival abilities from a molecular point of view. Results showed an immediate, time-limited and serovar-dependent reduction of bacterial viability. In the case of S. Senftenberg, the reduction in numbers was observed for up to 4 h of incubation in the presence of 200 mg/l of AgNPs; on the contrary, S. Enteritidis and S. Hadar resulted to be inhibited for up to 48 h. Reverse transcription and polymerase chain reaction experiments demonstrated the constitutive expression of the plasmidic silver resistance determinant (SilB) by S. Senftenberg, thus suggesting the importance of a cautious use of AgNPs.

Losasso, Carmen; Belluco, Simone; Cibin, Veronica; Zavagnin, Paola; Micetic, Ivan; Gallocchio, Federica; Zanella, Michela; Bregoli, Lisa; Biancotto, Giancarlo; Ricci, Antonia

2014-01-01

381

Transformation of silver nanoparticles in fresh, aged, and incinerated biosolids.  

PubMed

The purpose of this research was to assess the chemical transformation of silver nanoparticles (AgNPs) in aged, fresh, and incinerated biosolids in order to provide information for AgNP life cycle analyses. Silver nanoparticles were introduced to the influent of a pilot-scale wastewater (WW) treatment system consisting of a primary clarifier (PC), aeration basin, and secondary clarifier. The partitioning of the AgNPs between the aqueous and solid phases in the system was monitored. Less than 3% of the total AgNPs introduced into the PC were measured at the overflow of the PC. Biosolids were collected from the pilot-scale system for silver analyses, including Ag concentration and speciation. Additionally, biosolids were collected from a publically owned treatment works (POTW). The POTW biosolids were spiked with AgNPs, AgNO3, and Ag2S. One set of the spiked POTW biosolids was aged for one month, and another set was analyzed within 24 h via X-ray absorption spectroscopy (XAS) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDX) in order to determine Ag chemical speciation and elemental associations. Replicates of the aged and 24-h samples were also incinerated at 850 °C for 4 h. The residual ash was analyzed by XAS and SEM-EDX. The results show that AgNPs are converted to Ag-sulfur (as sulfide and sulfhydryl) species in fresh and aged biosolids, which is in agreement with other studies on AgNPs in biosolids. Results from linear combination fitting of the XAS data for incinerated biosolids show that a significant proportion of the spiked silver (30-50%) is converted to elemental Ag in the incineration process. In addition to elemental Ag, the results suggest the presence of additional Ag-S complexes such as Ag2SO4 (up to 25%), and silver associated with sulfhydryl groups (26-50%) in the incinerated biosolids. Incinerated biosolids spiked with AgNO3 and Ag2S exhibited similar transformations. These transformations of AgNPs should be accounted for in life-cycle analyses of AgNPs and in management decisions regarding the disposal of incinerated biosolids. PMID:23561507

Impellitteri, Christopher A; Harmon, Stephen; Silva, R Gune; Miller, Bradley W; Scheckel, Kirk G; Luxton, Todd P; Schupp, Donald; Panguluri, Srinivas

2013-08-01

382

Interactive effects of silver nanoparticles and phosphorus on phytoplankton growth in natural waters.  

PubMed

Increasing amounts of silver nanoparticles (AgNPs) are expected to enter the aquatic ecosystems where their effects on natural phytoplankton communities are poorly understood. We investigated the effects of AgNPs and its interactions with phosphorus (P) supply on the growth kinetics and stoichiometry of natural phytoplankton. Lake water was dosed with AgNPs (carboxy-functionalized capping agent; ?10-nm particle size; ?20% Ag w/w) at four different concentrations and five P concentrations and incubated in situ for 3 days. A treatment with ionic silver (AgNO3) was used as a positive control. We found that growth rates, calculated from changes in seston carbon and chlorophyll, responded significantly and interactively (p < 0.0001) to both AgNPs and P. AgNPs reduced the maximum phytoplankton growth rates by 11-85%. In the positive control, no or very little growth was observed. Inhibition of growth rates after exposure to Ag might be related to the reduction in chlorophyll and the inhibition of C and N acquisition rather than P uptake mechanisms. AgNPs, P supply and their interactions also significantly (p < 0.0001) reduced sestonic C:P and N:P ratios and increased C:N, C:Chl and cell-bound Ag stoichiometry. Our results indicate that fate and toxicity of AgNP will vary with phosphorus pollution level in aquatic ecosystems. PMID:24628458

Das, Pranab; Metcalfe, Chris D; Xenopoulos, Marguerite A

2014-04-15

383

Biosynthesis and characterization of silver nanoparticles using panchakavya, an Indian traditional farming formulating agent.  

PubMed

Synthesis of silver nanoparticles (AgNPs) with biological properties is of vast significance in the development of scientifically valuable products. In the present study, we describe simple, unprecedented, nontoxic, eco-friendly, green synthesis of AgNPs using an Indian traditional farming formulating agent, panchakavya. Silver nitrate (1 mM) solution was mixed with panchakavya filtrate for the synthesis of AgNPs. The nanometallic dispersion was characterized by surface plasmon absorbance measuring 430 nm. Transmission electron microscopy showed the morphology and size of the AgNPs. Scanning electron microscopy-energy-dispersive spectroscopy and X-ray diffraction analysis confirmed the presence of AgNPs. Fourier transform infrared spectroscopy analysis revealed that proteins in the panchakavya were involved in the reduction and capping of AgNPs. In addition, we studied the antibacterial activity of synthesized AgNPs. The synthesized AgNPs (1-4 mM) extensively reduced the growth rate of antibiotic resistant bacteria such as Aeromonas sp., Acinetobacter sp., and Citrobacter sp., according to the increasing concentration of AgNPs. PMID:24741307

Govarthanan, Muthusamy; Selvankumar, Thangasamy; Manoharan, Koildhasan; Rathika, Rajiniganth; Shanthi, Kuppusamy; Lee, Kui-Jae; Cho, Min; Kamala-Kannan, Seralathan; Oh, Byung-Taek

2014-01-01

384

Development of silver nanoparticle loaded antibacterial polymer mesh using plasma polymerization process.  

PubMed

Plasma polymerized polyacrylic acid (PPAA) was deposited on a polymer substrate, namely polyethylene terephthalate (PET) mesh, for entrapment of silver nanoparticle (Ag-NP) in order to achieve antibacterial property to the material. Carboxylic groups of PPAA act as anchor as well as capping and stabilizing agents for Ag-NPs synthesized by chemical reduction method using NaBH(4) as a reducing agent. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and water contact angle analysis were used to characterize the PPAA coatings. The Ag-NPs loaded polymer samples were characterized by UV-visible spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray, and XPS techniques. XPS analysis showed ~1.0 at.% loading of Ag-NPs on to the PPAA-PET-mesh, which was composed of 79% zero-valent (Ag°) and 21% oxidized nano-Ag (Ag(+) ). The plasma processed PET meshes samples were tested for antibacterial activity against two bacterial strains, namely Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). Qualitative and quantitative tests showed that silver containing PPAA-PET meshes exhibit excellent antibacterial property against the tested bacteria with percent reduction of bacterial concentration >99%, compared to the untreated PET mesh. PMID:23015534

Kumar, Virendra; Jolivalt, Claude; Pulpytel, Jerome; Jafari, Reza; Arefi-Khonsari, Farzaneh

2013-04-01

385

An easy route to prepare carbon black–silver hybrid catalysts for electro-catalytic oxidation of hydrazine  

Microsoft Academic Search

Carbon black–silver hybrid catalysts were easily synthesized by a mixing method of acid-oxidized carbon black and the colloidal dispersion of silver nanoparticles. The silver colloidal dispersion was pre-synthesized by a chemical reduction of silver nitrate by dimethyl sulfoxide in the presence of trisodium citrate dihydrate as capping agents. In the mixing method, approx. 6.0 nm diameters of silver nanoparticles with face-centered

Chang Tan; Feng Wang; Jingjun Liu; Yongbin Zhao; Jianjun Wang; Lianghu Zhang; Ki Chul Park; Morinobu Endo

2009-01-01

386

Biosynthesis of silver nanoparticles using lemon leaves extract and its application for antimicrobial finish on fabric  

NASA Astrophysics Data System (ADS)

Preparation of silver nanoparticles have been carried out using aqueous extract of lemon leaves ( Citrus limon) which acts as reducing agent and encapsulating cage for the silver nanoparticles. These silver nanoparticles have been used for durable textile finish on cotton and silk fabrics. Remarkable antifungal activity has been observed in the treated fabrics. The antimicrobial activity of silver nanoparticles derived from lemon leaves showed enhancement in activity due to synergistic effect of silver and essential oil components of lemon leaves. The present investigation shows the extracellular synthesis of highly stable silver nanoparticles by biotransformation using the extract of lemon leaves by controlled reduction of the Ag+ ion to Ag0. Further the silver nanoparticles were used for antifungal treatment of fabrics which was tested by antifungal activity assessment of textile material by Agar diffusion method against Fusarium oxysporum and Alternaria brassicicola. Formation of the metallic nanoparticles was established by FT-IR, UV-Visible spectroscopy, transmission electron microscopy, scanning electron microscopy, atomic force microscopy.

Vankar, Padma S.; Shukla, Dhara

2012-06-01

387

Bacterial flagella as biotemplate for the synthesis of silver nanoparticle impregnated bionanomaterial  

NASA Astrophysics Data System (ADS)

The present study was carried out to synthesize one dimensional silver nanoparticle impregnated flagellar bionanomaterial. Flagella was isolated from Salmonella typhimurium and depolymerised into flagellin monomers. The flagellin monomers were repolymerised again into flagella using suitable technique. The molecular weight of native (NF) and polymerized flagella (PF) was determined using polyacrylamide gel electrophoresis. The NF and PF were used as a template, over which silver nanoparticles were impregnated using in situ chemical reduction process. The synthesized flagellar-silver nanoparticle bionanomaterials were characterized using UV-vis, FT-IR Raman and XRD spectroscopy, and High resolution transmission electron microscopy (HR-TEM). The characterization studies confirmed the attachment of silver nanoparticles over flagella and repolymerised flagella. The size of the silver nanoparticles on the flagella and repolymerised flagella varied and was in the range of 3-11 nm. I-V characteristics of the bionanomaterials were analyzed using Kethley meter which indicated the increase of conductivity after impregnation of silver nanoparticles. The results indicated that flagellar-silver nanoparticle bionanomaterials can be used as a potential one dimensional bionanomaterials for various applications.

Gopinathan, Priya; Ashok, Anuradha M.; Selvakumar, R.

2013-07-01

388

Synthesis of Mn doped ZnO nanoparticles with biocompatible capping  

NASA Astrophysics Data System (ADS)

Free standing nanoparticles of ZnO doped with transition metal ion Mn have been prepared by solid state reaction method at 500 °C. X-ray diffraction (XRD) analysis confirmed high quality monophasic wurtzite hexagonal structure with particle size of 50 nm and no signature of dopant as separate phase. Incorporation of Mn has been confirmed with EDS. Bio-inorganic interface was created by capping the nanoparticles with heteromultifunctional organic stabilizer mercaptosuccinic acid (MSA). The surface morphological studies by scanning electron microscopy (SEM) showed formation of spherical particles and the nanoballs grow in size uniformly with MSA capping. MSA capping has been confirmed w