WorldWideScience

Sample records for monolayer-protected gold nanoparticle

  1. Surface effects of monolayer-protected gold nanoparticles on the redox reactions between ferricyanide and thiosulfate

    Institute of Scientific and Technical Information of China (English)

    LI Di; SUN Chunyan; HUANG Yunjie; LI Jinghong; CHEN Shaowei

    2005-01-01

    Electron transfer through the self-assembled monolayers (SAMs) on gold nanoparticles is investigated by using the monolayer protected gold nanoclusters (MPCs) as electron-transfer mediators. 3-Mercaptopropionic acid (MPA) and 11-meraptoundecanoic acid (MUA) MPCs were employed to catalyze the redox reaction between potassium ferricyanide and sodium thiosulfate. The catalytic mechanism was proposed that the MPCs act as diffusing electron-mediators and electron transfers to and from the MPCs surface. Therefore the electron transfer rate through the capping layers would be proportional to the MPCs catalyzed reaction rate, which was monitored by the UV absorbance of ferricyanide. The calculated apparent rate constant was orders of magnitude smaller than that of the maximum of tunneling current, which was attributed to the splited energy level of the nanoscale particles.

  2. The Shell Structure Effect on the Vapor Selectivity of Monolayer-Protected Gold Nanoparticle Sensors

    Directory of Open Access Journals (Sweden)

    Rui-Xuan Huang

    2014-02-01

    Full Text Available Four types of monolayer-protected gold nanoclusters (MPCs were synthesized and characterized as active layers of vapor sensors. An interdigitated microelectrode (IDE and quartz crystal microbalance (QCM were used to measure the electrical resistance and mass loading changes of MPC films during vapor sorption. The vapor sensing selectivity was influenced by the ligand structure of the monolayer on the surface of gold nanoparticles. The responses of MPC-coated QCM were mainly determined according to the affinity between the vapors and surface ligands of MPCs. The responses to the resistance changes of the MPC films were due to the effectiveness of the swelling when vapor was absorbed. It was observed that resistive sensitivity to polar organics could be greatly enhanced when the MPC contained ligands that contain interior polar functional groups with exterior nonpolar groups. This finding reveals that reducing interparticle attraction by using non-polar exterior groups could increase effective swelling and therefore enhance the sensitivity of MPC-coated chemiresistors.

  3. Mechanism of lipid bilayer penetration by mixed monolayer-protected gold nanoparticles

    Science.gov (United States)

    van Lehn, Reid; Atukorale, Prabhani; Carney, Randy; Stellacci, Francesco; Irvine, Darrell; Alexander-Katz, Alfredo

    2013-03-01

    Recently, gold nanoparticles (AuNPs) protected by a binary mixture of hydrophobic and hydrophilic alkanethiol ligands were observed to spontaneously penetrate cellular membranes via a non-specific mechanism. Penetration was observed even at low temperatures and in the presence of endocytotic inhibitors, implying that AuNPs crossed the membrane by a non-endocytotic process. Furthermore, penetration was shown to depend on the amphiphilicity and nanoscale morphology of the protecting monolayer. In this work, we use a variety of simulation techniques to elucidate the mechanism of lipid bilayer penetration and compare our results to experiments with lipid vesicles. We show that these AuNPs can stably embed within lipid bilayers by ``snorkeling'' charges out of the bilayer core; the stability of such a state is a function of particle size, the composition of the protecting monolayer, and other environmental conditions. We use detailed simulations to analyze structural changes in the surrounding lipids and show that the energy barrier for embedding is considerably reduced in the presence of bilayer defects. We expect that these results will enable the design of novel drug delivery carriers and biosensors.

  4. Mass spectrometric analysis of monolayer protected nanoparticles

    Science.gov (United States)

    Zhu, Zhengjiang

    Monolayer protected nanoparticles (NPs) include an inorganic core and a monolayer of organic ligands. The wide variety of core materials and the tunable surface monolayers make NPs promising materials for numerous applications. Concerns related to unforeseen human health and environmental impacts of NPs have also been raised. In this thesis, new analytical methods based on mass spectrometry are developed to understand the fate, transport, and biodistributions of NPs in the complex biological systems. A laser desorption/ionization mass spectrometry (LDI-MS) method has been developed to characterize the monolayers on NP surface. LDI-MS allows multiple NPs taken up by cells to be measured and quantified in a multiplexed fashion. The correlations between surface properties of NPs and cellular uptake have also been explored. LDI-MS is further coupled with inductively coupled plasma mass spectrometry (ICP-MS) to quantitatively measure monolayer stability of gold NPs (AuNPs) and quantum dots (QDs), respectively, in live cells. This label-free approach allows correlating monolayer structure and particle size with NP stability in various cellular environments. Finally, uptake, distribution, accumulation, and excretion of NPs in higher order organisms, such as fish and plants, have been investigated to understand the environmental impact of nanomaterials. The results indicate that surface chemistry is a primary determinant. NPs with hydrophilic surfaces are substantially less toxic and present a lower degree of bioaccumulation, making these nanomaterials attractive for sustainable nanotechnology.

  5. Molecular tilt on monolayer-protected nanoparticles

    KAUST Repository

    Giomi, L.

    2012-02-01

    The structure of the tilted phase of monolayer-protected nanoparticles is investigated by means of a simple Ginzburg-Landau model. The theory contains two dimensionless parameters representing the preferential tilt angle and the ratio ε between the energy cost due to spatial variations in the tilt of the coating molecules and that of the van der Waals interactions which favors the preferential tilt. We analyze the model for both spherical and octahedral particles. On spherical particles, we find a transition from a tilted phase, at small ε, to a phase where the molecules spontaneously align along the surface normal and tilt disappears. Octahedral particles have an additional phase at small ε characterized by the presence of six topological defects. These defective configurations provide preferred sites for the chemical functionalization of monolayer-protected nanoparticles via place-exchange reactions and their consequent linking to form molecules and bulk materials. Copyright © EPLA, 2012.

  6. Synthesis of nanoparticle-cored dendrimers by convergent dendritic functionalization of monolayer-protected nanoparticles.

    Science.gov (United States)

    Shon, Young-Seok; Choi, Daeock; Dare, Jonathan; Dinh, Tuong

    2008-06-01

    This article presents a synthesis method for nanoparticle-cored dendrimers (NCDs), which have dendritic architectures around a monolayer-protected gold nanoparticle. The synthesis method is based on a strategy in which the synthesis of monolayer-protected nanoparticles is followed by adding dendrons on functionalized nanoparticles by a single coupling reaction. NMR spectroscopy, IR spectroscopy, and thermogravimetric analysis (TGA) characterizations confirmed the successful coupling reaction between dendrons with different generations ([G1], [G2], and [G3]) and COOH-functionalized nanoparticles ( approximately Au201L71). The dendrimer wedge density also could be controlled by reacting nanoparticles having different loading of COOH groups ( approximately 60 and approximately 10% COOH of the 71 ligands per gold nanoparticle) with functionalized dendrons. Transmission electron microscope results showed that this synthesis strategy maintains the average size of the nanoparticle core during dendron coupling reactions. This control over the composition and core size makes the systematic study of NCDs with different generations possible. The chemical stability of NCDs was found to be affected by dendron generation around the nanoparticle core. The current-potential response of NCD films on microelectrode arrays exhibited better electrical conductivity for NCDs with lower dendron generation.

  7. Synthesis and characterization of mixed monolayer protected gold nanorods and their Raman activities

    Energy Technology Data Exchange (ETDEWEB)

    Mlambo, Mbuso [Molecular Science Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits 2050 (South Africa); Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, Private Bag X3015, Randburg 2125 (South Africa); Mdluli, Phumlani S.; Shumbula, Poslet; Mpelane, Siyasanga [Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, Private Bag X3015, Randburg 2125 (South Africa); Moloto, Nosipho, E-mail: Nosipho.Moloto@wits.ac.za [Molecular Science Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits 2050 (South Africa); Skepu, Amanda; Tshikhudo, Robert [Nanotechnology Innovation Centre, Advanced Materials Division, Mintek, Private Bag X3015, Randburg 2125 (South Africa)

    2013-10-15

    Graphical abstract: Gold nanorods surface functionalization. - Highlights: • Mixed monolayer protected gold nanorods. • Surface enhanced Raman spectroscopy. • HS-(CH{sub 2}){sub 11}-NHCO-coumarin as a Raman active compound. - Abstract: The cetyltrimethylammonium bromide (CTAB) gold nanorods (AuNRs) were prepared by seed-mediated route followed by the addition of a Raman active compound (HS-(CH{sub 2}){sub 11}-NHCO-coumarin) on the gold nanorods surfaces. Different stoichiometric mixtures of HS-(CH{sub 2}){sub 11}-NHCO-coumarin and HS-PEG-(CH{sub 2}){sub 11}COOH were evaluated for their Raman activities. The lowest stoichiometric ratio HS-(CH{sub 2}){sub 11}-NHCO-coumarin adsorbed on gold nanorods surface was detected and enhanced by Raman spectroscopy. The produced mixed monolayer protected gold nanorods were characterized by UV-vis spectrometer for optical properties, transmission electron microscope (TEM) for structural properties (shape and aspect ratio) and their zeta potentials (charges) were obtained from ZetaSizer to determine the stability of the produced mixed monolayer protected gold nanorods. The Raman results showed a surface enhanced Raman scattering (SERS) enhancement at the lowest stoichiometric ratio of 1% HS-(CH{sub 2}){sub 11}-NHCO-coumarin compared to high ratio of 50% HS-(CH{sub 2}){sub 11}-NHCO-coumarin on the surface of gold nanorods.

  8. Facile Attachment of TAT Peptide on Gold Monolayer Protected Clusters: Synthesis and Characterization

    Directory of Open Access Journals (Sweden)

    Ndabenhle M. Sosibo

    2015-07-01

    Full Text Available High affinity thiolate-based polymeric capping ligands are known to impart stability onto nanosized gold nanoparticles. Due to the stable gold-sulfur bond, the ligand forms a protective layer around the gold core and subsequently controls the physicochemical properties of the resultant nanogold mononuclear protected clusters (AuMPCs. The choice of ligands to use as surfactants for AuMPCs largely depends on the desired degree of hydrophilicity and biocompatibility of the MPCs, normally dictated by the intended application. Subsequent surface modification of AuMPCs allows further conjugation of additional biomolecules yielding bilayer or multilayered clusters suitable for bioanalytical applications ranging from targeted drug delivery to diagnostics. In this study, we discuss our recent laboratory findings on a simple route for the introduction of Trans-Activator of Transcription (TAT peptide onto the surface of biotin-derivatised gold MPCs via the biotin-strepavidin interaction. By changing the surface loading of biotin, controlled amounts of TAT could be attached. This bioconjugate system is very attractive as a carrier in intercellular delivery of various delivery cargoes such as antibodies, proteins and oligonucleotides.

  9. Mixed monolayer protected gold atom-oxide cluster synthesis and characterization

    Science.gov (United States)

    Nambiar, Sindhu R.; Aneesh, Padamadathil K.; Sukumar, Chinthu; Rao, Talasila P.

    2012-06-01

    Small atomic gold clusters in solution, Aun, stabilized by cetyl trimethylammonium bromide (CTAB) and cysteine, have been synthesized potentiodynamically in quiescent aqueous solutions. The electrodissolution of gold to gold ions during an anodic scan and subsequent cluster formation during a cathodic scan in underpotential (UPDD) and overpotential dissolution-deposition (OPDD) regions were studied. The experimental potentiodynamic I-E profiles and chronoamperometric i-t transients are fit into reported theoretical models of adsorption and electrocrystallization. The plausible application of clusters/cluster film to cysteine sensing based on fluorescence quenching and square wave stripping voltammetry is demonstrated.Small atomic gold clusters in solution, Aun, stabilized by cetyl trimethylammonium bromide (CTAB) and cysteine, have been synthesized potentiodynamically in quiescent aqueous solutions. The electrodissolution of gold to gold ions during an anodic scan and subsequent cluster formation during a cathodic scan in underpotential (UPDD) and overpotential dissolution-deposition (OPDD) regions were studied. The experimental potentiodynamic I-E profiles and chronoamperometric i-t transients are fit into reported theoretical models of adsorption and electrocrystallization. The plausible application of clusters/cluster film to cysteine sensing based on fluorescence quenching and square wave stripping voltammetry is demonstrated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30446e

  10. Organo-Soluble Porphyrin Mixed Monolayer-Protected Gold Nanorods with Intercalated Fullerenes

    Science.gov (United States)

    2012-03-16

    example, with dye molecules on GNRs, photothermal therapy and fluorescence imaging can be accomplished simultaneously.4b Although the coupling of dye...W.; El-Sayed, M. A. Cancer Cell Imaging and Photothermal Therapy in The Near-Infrared Region by Using Gold Nanorods. J. Am. Chem. Soc. 2006, 128...pubs.acs.org on March 20, 2012 Just Accepted “Just Accepted” manuscripts have been peer- reviewed and accepted for publication. They are posted online prior to

  11. Structural Order in Ultrathin Films of the Monolayer Protected Clusters Based Upon 4-nm Gold Nanocrystals: An Experimental and Theoretical Study

    Science.gov (United States)

    Bhattarai, Nabraj; Khanal, Subarna; Bahena, Daniel; Olmos-Asar, Jimena A.; Ponce, Arturo; Whetten, Robert L.; Mariscal, Marcelo M.; Jose-Yacaman, Miguel

    2014-01-01

    The structural order in ultrathin films of monolayer protected clusters (MPCs) is important in a number of application areas but can be difficult to demonstrate by conventional methods, particularly when the metallic core dimension, d, is in the intermediate size-range, 1.5 < d < 5.0 nm. Here, improved techniques for the synthesis of monodisperse thiolate-protected gold nanoparticles have made possible the production of dodecane-thiolate saturated ~ 4 ± 0.5 nm Au clusters with single-crystal core structure and morphology. An ultrathin ordered film or superlattice of these nanocrystal-core MPCs is prepared and investigated using aberration corrected scanning/transmission electron microscopy (STEM) which allowed imaging of long-range hexagonally ordered superlattices of the nanocrystals, separated by the thiolate groups. The lattice constants determined by direct imaging are in good agreement with those determined by small-angle electron diffraction. The STEM image revealed the characteristic grain boundary (GB) with sigma (Σ) 13 in the interface between two crystals. The formation and structures found are interpreted on the basis of theoretical calculations employing molecular dynamics (MD) simulations and coarse-grained (CG) approach. PMID:24875295

  12. Kinetic evaluation of highly active supported gold catalysts prepared from monolayer-protected clusters: an experimental Michaelis-Menten approach for determining the oxygen binding constant during CO oxidation catalysis.

    Science.gov (United States)

    Long, Cormac G; Gilbertson, John D; Vijayaraghavan, Ganesh; Stevenson, Keith J; Pursell, Christopher J; Chandler, Bert D

    2008-08-06

    Thiol monolayer-protected Au clusters (MPCs) were prepared using dendrimer templates, deposited onto a high-surface-area titania, and then the thiol stabilizers were removed under H2/N2. The resulting Au catalysts were characterized with transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy of adsorbed CO. The Au catalysts prepared via this route displayed minimal particle agglomeration during the deposition and activation steps. Structural data obtained from the physical characterization of the Au catalysts were comparable to features exhibited from a traditionally prepared standard Au catalyst obtained from the World Gold Council (WGC). A differential kinetic study of CO oxidation catalysis by the MPC-prepared Au and the standard WGC catalyst showed that these two catalyst systems have essentially the same reaction order and Arrhenius apparent activation energies (28 kJ/mol). However, the MPC-prepared Au catalyst shows 50% greater activity for CO oxidation. Using a Michaelis-Menten approach, the oxygen binding constants for the two catalyst systems were determined and found to be essentially the same within experimental error. To our knowledge, this kinetic evaluation is the first experimental determination of oxygen binding by supported Au nanoparticle catalysts under working conditions. The values for the oxygen binding equilibrium constant obtained from the Michaelis-Menten treatment (ca. 29-39) are consistent with ultra-high-vacuum measurements on model catalyst systems and support density functional theory calculations for oxygen binding at corner or edge atoms on Au nanoparticles and clusters.

  13. Removal of phase transfer agent leads to restricted dynamics of alkyl chains in monolayer protected clusters

    Indian Academy of Sciences (India)

    V R Rajeev Kumar; R Mukhopadhyay; T Pradeep

    2008-11-01

    The effect of phase transfer agent in the dynamics of monolayer protected gold nanoparticles has been investigated by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies. The experiments were performed with octadecane thiol and dodecane thiol protected gold nanoparticles. The materials prepared were characterized by UV-Visible spectroscopy, transmission electron microscopy and IR spectroscopy. Repeated purification of the monolayer protected gold clusters made the alkyl chains defect-free. Such effects are reflected in the infrared spectra. Interdigitation of the monolayers that followed the purification leads to alkyl chains with limited mobility. This was reflected in 13C and 1H NMR linewidths. The NMR measurements indicate that the removal of phase transfer agent affects the dynamics of isolated clusters and those with interdigitated monolayers in different ways.

  14. Chemistry for oncotheranostic gold nanoparticles.

    Science.gov (United States)

    Trouiller, Anne Juliette; Hebié, Seydou; El Bahhaj, Fatima; Napporn, Teko W; Bertrand, Philippe

    2015-06-24

    This review presents in a comprehensive ways the chemical methods used to functionalize gold nanoparticles with focus on anti-cancer applications. The review covers the parameters required for the synthesis gold nanoparticles with defined shapes and sizes, method for targeted delivery in tumours, and selected examples of anti-cancers compounds delivered with gold nanoparticles. A short survey of bioassays for oncology based on gold nanoparticles is also presented.

  15. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  16. Gold Nanoparticle Microwave Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, Kelsie E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Christian, Jonathan H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coopersmith, Kaitlin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Washington, II, Aaron L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Murph, Simona H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, a reduction in reaction time from 10 minutes to 1 minute, maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  17. Green Synthesis of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Hamid Reza Ghorbani

    2015-03-01

    Full Text Available There is an increased interest in understanding the toxicity and rational design of gold nanoparticles for biomedical applications in recent years. In this study gold nanoparticles were synthesized using dextrose as a reducing agent. The gold nanoparticles displayed characteristic Surface Plasmon Resonance peak at around 550 nm having a mean particle size of 75±30 nm. In order to identify and analyze nanoparticles, UV–Vis spectroscopy, Scanning electron microscopy (SEM, and dynamic light scattering (DLS were used.

  18. Directed Assembly of Gold Nanoparticles

    DEFF Research Database (Denmark)

    Westerlund, Axel Rune Fredrik; Bjørnholm, Thomas

    2009-01-01

    As a complement to common "top-down" lithography techniques, "bottom-up" assembly techniques are emerging as promising tools to build nanoscale structures in a predictable way. Gold nanoparticles that are stable and relatively easy to synthesize are important building blocks in many such structures...... due to their useful optical and electronic properties. Programmed assembly of gold nanoparticles in one, two, and three dimensions is therefore of large interest. This review focuses on the progress from the last three years in the field of directed gold nanoparticle and nanorod assembly using...

  19. Atomistic Simulations of Functional Au-144(SR)(60) Gold Nanoparticles in Aqueous Environment

    DEFF Research Database (Denmark)

    Heikkila, E.; Gurtovenko, A. A.; Martinez-Seara, H.

    2012-01-01

    Charged monolayer-protected gold nanoparticles (AuNPs) have been studied in aqueous solution by performing atomistic molecular dynamics simulations at physiological temperature (310 K). Particular attention has been paid to electrostatic properties that modulate the formation of a complex comprised...... of the nanoparticle together with surrounding ions and water. We focus on Au-144 nanoparticles that comprise a nearly spherical Au core (diameter similar to 2 nm), a passivating Au-S interface, and functionalized alkanethiol chains. Cationic and anionic AuNPs have been modeled with amine and carboxyl terminal groups...... potential displays a minimum for AuNP- at 1.9 nm from the center of the nanoparticle, marking a preferable location for Na+, while the AuNP+ potential (affecting the distribution of Cl-) rises almost monotonically with a local maximum. Comparison to Debye-Huckel theory shows very good agreement for radial...

  20. Gold Nanoparticle Mediated Phototherapy for Cancer

    Directory of Open Access Journals (Sweden)

    Cuiping Yao

    2016-01-01

    Full Text Available Gold nanoparticles exhibit very unique physiochemical and optical properties, which now are extensively studied in range of medical diagnostic and therapeutic applications. In particular, gold nanoparticles show promise in the advancement of cancer treatments. This review will provide insights into the four different cancer treatments such as photothermal therapy, gold nanoparticle-aided photodynamic therapy, gold nanoparticle-aided radiation therapy, and their use as drug carrier. We also discuss the mechanism of every method and the adverse effects and its limitations.

  1. Preparation of Gold Nanoparticles Protected with Polyelectrolyte

    Institute of Scientific and Technical Information of China (English)

    Xu Ping SUN; Zhe Ling ZHANG; Bai Lin ZHANG; Xian Dui DONG; Shao Jun DONG; Er Kang WANG

    2003-01-01

    Gold nanoparticles were synthesized through the reduction of tetrachlorauric acid (HAuCl4) by NaBH4, with polyethyleneimine(PEI) as stabilizer. The nanoparticles were characterized by UV-vis spectroscopy and atomic force microscopy(AFM).

  2. Ordering Gold Nanoparticles with DNA Origami Nanoflowers.

    Science.gov (United States)

    Schreiber, Robert; Santiago, Ibon; Ardavan, Arzhang; Turberfield, Andrew J

    2016-08-23

    Nanostructured materials, including plasmonic metamaterials made from gold and silver nanoparticles, provide access to new materials properties. The assembly of nanoparticles into extended arrays can be controlled through surface functionalization and the use of increasingly sophisticated linkers. We present a versatile way to control the bonding symmetry of gold nanoparticles by wrapping them in flower-shaped DNA origami structures. These "nanoflowers" assemble into two-dimensonal gold nanoparticle lattices with symmetries that can be controlled through auxiliary DNA linker strands. Nanoflower lattices are true composites: interactions between the gold nanoparticles are mediated entirely by DNA, and the DNA origami will fold into its designed form only in the presence of the gold nanoparticles.

  3. High-Yield Excited Triplet States in Pentacene Self-Assembled Monolayers on Gold Nanoparticles through Singlet Exciton Fission.

    Science.gov (United States)

    Kato, Daiki; Sakai, Hayato; Tkachenko, Nikolai V; Hasobe, Taku

    2016-04-18

    One of the major drawbacks of organic-dye-modified self-assembled monolayers on metal nanoparticles when employed for efficient use of light energy is the fact that singlet excited states on dye molecules can be easily deactivated by means of energy transfer to the metal surface. In this study, a series of 6,13-bis(triisopropylsilylethynyl)pentacene-alkanethiolate monolayer protected gold nanoparticles with different particle sizes and alkane chain lengths were successfully synthesized and were employed for the efficient generation of excited triplet states of the pentacene derivatives by singlet fission. Time-resolved transient absorption measurements revealed the formation of excited triplet states in high yield (172±26 %) by suppressing energy transfer to the gold surface.

  4. CO oxidation on gold nanoparticles: Theoretical studies

    DEFF Research Database (Denmark)

    Remediakis, Ioannis; Lopez, Nuria; Nørskov, Jens Kehlet

    2005-01-01

    We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold...

  5. [Biosynthesis of gold nanoparticles by Azospirillum brasilense].

    Science.gov (United States)

    Kupriashina, M A; Vetchinkina, E P; Burov, A M; Ponomareva, E G; Nikitina, V E

    2014-01-01

    Plant-associated nitrogen-fixing soil bacteria Azospirillum brasilense were shown to reduce the gold of chloroauric acid to elemental gold, resulting in formation of gold nanoparicles. Extracellular phenoloxidizing enzymes (laccases and Mn peroxidases) were shown to participate in reduction of Au+3 (HAuCl4) to Au(0). Transmission electron microscopy revealed accumulation of colloidal gold nanoparticles of diverse shape in the culture liquid of A. brasilense strains Sp245 and Sp7. The size of the electron-dense nanospheres was 5 to 50 nm, and the size of nanoprisms varied from 5 to 300 nm. The tentative mechanism responsible for formation of gold nanoparticles is discussed.

  6. Resonance scattering spectroscopy of gold nanoparticle

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gold nanoparticles in diameter of 10-95 nm have been prepared by Frens procedure, all of which exhibit a resonance scattering peak at 580 nm. The mechanism of resonance scattering for gold nanoparticle has been considered according to the wave motion theory of nanoparticle in liquid. The principle of superamolecular interface energy band(SIEB) has been set up and utilized to explain the relationship between the diameter and colors for gold nanoparticle in liquid. A novel spectrophotometric ruler for the determination of the diameter has been proposed according to the relationship of the maximum absorption wavelength and diameter.

  7. Poly(ethylene glycol)- and carboxylate-functionalized gold nanoparticles using polymer linkages: single-step synthesis, high stability, and plasmonic detection of proteins.

    Science.gov (United States)

    Park, Garam; Seo, Daeha; Chung, Im Sik; Song, Hyunjoon

    2013-11-05

    Gold nanoparticles with suitable surface functionalities have been widely used as a versatile nanobioplatform. However, functionalized gold nanoparticles using thiol-terminated ligands have a tendency to aggregate, particularly in many enzymatic reaction buffers containing biological thiols, because of ligand exchange reactions. In the present study, we developed a one-step synthesis of poly(ethylene glycol) (PEG)ylated gold nanoparticles using poly(dimethylaminoethyl methacrylate) (PDMAEMA) in PEG as a polyol solvent. Because of the chelate effect of polymeric functionalities on the gold surface, the resulting PEGylated gold nanoparticles (Au@P-PEG) are very stable under the extreme conditions at which the thiol-monolayer-protected gold nanoparticles are easily coagulated. Using the solvent mixture of PEG and ethylene glycol (EG) and subsequent hydrolysis, gold nanoparticles bearing mixed functionalities of PEG and carboxylate are generated. The resulting particles exhibit selective adsorption of positively charged chymotrypsin (ChT) without nonselective adsorption of bovine serum albumin (BSA). The present nanoparticle system has many advantages, including high stability, simple one-step synthesis, biocompatibility, and excellent binding specificity; thus, this system can be used as a versatile platform for potential bio-related applications, such as separation, sensing, imaging, and assays.

  8. Gold nanoparticles produced in a microalga

    Science.gov (United States)

    Luangpipat, Tiyaporn; Beattie, Isabel R.; Chisti, Yusuf; Haverkamp, Richard G.

    2011-12-01

    An efficient biological route to production of gold nanoparticles which allows the nanoparticles to be easily recovered remains elusive. Live cells of the green microalga Chlorella vulgaris were incubated with a solution of gold chloride and harvested by centrifugation. Nanoparticles inside intact cells were identified by transmission electron microscopy and confirmed to be metallic gold by synchrotron based X-ray powder diffraction and X-ray absorption spectroscopy. These intracellular gold nanoparticles were 40-60 nm in diameter. At a concentration of 1.4% Au in the alga, a better than 97% recovery of the gold from solution was achieved. A maximum of 4.2% Au in the alga was obtained. Exposure of C. vulgaris to solutions containing dissolved salts of palladium, ruthenium, and rhodium also resulted in the production of the corresponding nanoparticles within the cells. These were surmised to be also metallic, but were produced at a much lower intracellular concentration than achieved with gold. Iridium was apparently toxic to the alga. No nanoparticles were observed using platinum solutions. C. vulgaris provides a possible route to large scale production of gold nanoparticles.

  9. CO oxidation on gold nanoparticles: Theoretical studies

    DEFF Research Database (Denmark)

    Remediakis, Ioannis; Lopez, Nuria; Nørskov, Jens Kehlet

    2005-01-01

    We present a summary of our theoretical results regarding CO oxidation on both oxide-supported and isolated gold nanoparticles. Using Density Functional Theory we have studied the adsorption of molecules and the oxidation reaction of CO on gold clusters. Low-coordinated sites on the gold...... nanoparticles can adsorb small inorganic molecules such as O2 and CO, and the presence of these sites is the key factor for the catalytic properties of supported gold nanoclusters. Other contributions, induced by the presence of the support, can provide parallel channels for the reaction and modulate the final...

  10. Functionalization of gold nanoparticles as antidiabetic nanomaterial.

    Science.gov (United States)

    Venkatachalam, M; Govindaraju, K; Mohamed Sadiq, A; Tamilselvan, S; Ganesh Kumar, V; Singaravelu, G

    2013-12-01

    In the present investigation, functionalization of gold nanoparticles synthesized using propanoic acid 2-(3-acetoxy-4,4,14-trimethylandrost-8-en-17-yl) (PAT) an active biocomponent isolated from Cassia auriculata is studied in detail. On reaction of PAT with aqueous HAuCl4, rapid formation of stable gold nanoparticles was achieved. Formation of gold nanoparticles was confirmed by UV-vis spectroscopy, XRD, GC-MS,FTIR, TEM and SEM with EDAX. Gold nanoparticles mostly were monodisperse, spherical in shape and ranged in size 12-41 nm. Gold nanoparticles synthesised using PAT was administered to alloxan (150 mg/kg body weight) induced diabetic male albino rats at different doses (0.25, 0.5, 0.75 and 1.0mg/kg body weight) for 28 days. Plasma glucose level, cholesterol and triglyceride were significantly (pgold nanoparticles at dosage of 0.5mg/kg body weight and plasma insulin increased significantly. The newly genre green gold nanoparticles exhibit remarkable protein tyrosine phosphatase 1B inhibitory activity.

  11. Current methods for synthesis of gold nanoparticles.

    Science.gov (United States)

    Herizchi, Roya; Abbasi, Elham; Milani, Morteza; Akbarzadeh, Abolfazl

    2016-01-01

    Metal nanoparticles, such as nanoparticles synthesized using gold, have numerous uncommon chemical and physical properties due to the effects of their quantum size and their large surface area, in comparison with other metal atoms or bulk metal. Gold nanoparticles (GNPs), in particular, are very attractive because of their size and shape-dependent properties. Metal nanoparticles have gathered extensive attention due to their uncommon properties and promising applications in photonics, electronics, biochemical sensing, and imaging. This review covers recent advances in the synthesis of GNPs.

  12. Functionalized Gold Nanoparticles and Their Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Shree R. Singh

    2011-06-01

    Full Text Available Metal nanoparticles are being extensively used in various biomedical applications due to their small size to volume ratio and extensive thermal stability. Gold nanoparticles (GNPs are an obvious choice due to their amenability of synthesis and functionalization, less toxicity and ease of detection. The present review focuses on various methods of functionalization of GNPs and their applications in biomedical research. Functionalization facilitates targeted delivery of these nanoparticles to various cell types, bioimaging, gene delivery, drug delivery and other therapeutic and diagnostic applications. This review is an amalgamation of recent advances in the field of functionalization of gold nanoparticles and their potential applications in the field of medicine and biology.

  13. Gold Nanoparticle Labels Amplify Ellipsometric Signals

    Science.gov (United States)

    Venkatasubbarao, Srivatsa

    2008-01-01

    The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

  14. Nonlinear optical studies of single gold nanoparticles

    NARCIS (Netherlands)

    Dijk, Meindert Alexander van

    2007-01-01

    Gold nanoparticles are spherical clusters of gold atoms, with diameters typically between 1 and 100 nanometers. The applications of these particles are rather diverse, from optical labels for biological experiments to data carrier for optical data storage. The goal of my project was to develop new

  15. Protein-mediated autoreduction of gold salts to gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Nivedita; Bhattacharya, Resham; Mukherjee, Priyabrata [Department of Biochemistry and Molecular Biology, College of Medicine, Mayo Clinic, Rochester, MN 55905 (United States)], E-mail: Mukherjee.Priyabrata@mayo.edu

    2008-09-01

    Here we report for the first time that proteins can function as unique reducing agents to produce gold nanoparticles from gold salts. We demonstrate that three different proteins, namely, bovine serum albumin (BSA), Rituximab (RIT-an anti-CD20 antibody) and Cetuximab (C225-anti-EGFR antibody), reduce gold salts to gold nanoparticles (GNP). Interestingly, among all the three proteins tested, only BSA can reduce gold salts to gold nanotriangles (GNT). BSA-induced formation of GNT can be controlled by carefully selecting the reaction condition. Heating or using excess of ascorbic acid (AA) as additional reducing agent shifts the reaction towards the formation of GNP with flower-like morphology, whereas slowing down the reaction either by cooling or by adding small amount of AA directs the synthesis towards GNT formation. GNT is formed only at pH 3; higher pHs (pH 7 and pH 10) did not produce any nanoparticles, suggesting the involvement of specific protein conformation in GNT formation. The nanomaterials formed by this method were characterized using UV-visible (UV-vis) spectroscopy and transmission electron microscopy (TEM). This is an important finding that will have uses in various nanotechnological applications, particularly in the green synthesis of novel nanomaterials based on protein structure.

  16. Alkanetelluroxide-protected gold nanoparticles.

    Science.gov (United States)

    Li, Ying; Silverton, Latoya C; Haasch, Richard; Tong, Yu Ye

    2008-07-15

    The synthesis and characterization of the first air-stable tellurium-containing ligand-protected gold nanoparticles (NPs) are reported. Although the synthesis largely followed the well-known Brust two-phase approach, the starting ligand was dioctyl ditelluride rather than alkanetellurol, which is an analogue of the widely used alkanethiol. Dioctyl ditelluride was used because alkanetellurol is unstable. The 1H and 13C NMR spectra, as well as infrared spectra (IR) of the formed Au NPs, indicated that the Te-Te bond in the starting ligand was broken but the octyl group was intact. This was further corroborated by the solid-state 125Te NMR spectrum that displayed a very broad and significantly downfield-shifted peak, indicating that tellurium was directly bound to the Au core. Furthermore, the O 1s and Te 3d XPS spectra of the Au NPs indicated that the capping ligands were octanetelluroxide. An average particle size of 2.7 nm diameter as measured by transmission electron microscopy (TEM) corresponded to an Au607 core. A two-step weight loss of approximately 22.2% in total was observed in the thermogravimetric analysis, which indicated about 53% ligand monolayer coverage (i.e., Au607(Te(=O)C8H17)133). Additionally, dioctyl ditelluride demonstrated an intriguing reductive power that led to a more sophisticated chemistry of forming the air-stable octanetelluroxide-protected gold NPs. It has been found that (1) when the ratio of Au to Te was about 1.5 a colorless intermediate state similar to Au(I)-SR (the intermediate state widely accepted in the synthesis of thiolate-protected Au NPs) could be obtained and (2) this kind of intermediate state played a key role in the formation of stable Au NPs.

  17. Coupling reaction on gold nanoparticle to yield polythiophene/gold nanoparticle alternate network film.

    Science.gov (United States)

    Tanaka, Manabu; Fujita, Remi; Nishide, Hiroyuki

    2009-01-01

    The novel gold nanoparticle, which was stabilized with pi-conjugated molecules bearing functional groups at the terminals, was prepared via conventional procedure by using 5-bromo-2,2'-bithiophene-5'-thiol as a stabilizer. The gold nanoparticle (ca. 3 nm-diameter) showed good dispersion stability in various organic solvents, and its electrochemical and spectroscopic study revealed peculiar properties originated in the pi-conjugated molecular stabilizer, bithiophene derivative. The Pd-catalyzed coupling reaction on the gold nanoparticle was first achieved by using the gold nanoparticle bearing bromo groups at the particle surface and the model boronic acid molecule, 5-formyl-2-thiopheneboronic acid, to yield the terthiophene derivatives on the gold nanoparticle. The 1H-NMR, UV, and TGA analysis supported the progress of the coupling reaction on the gold nanoparticle. This Pd-catalyzed coupling reaction was applied with the borate-terminated polythiophene to form polythiophene/gold nanoparticle alternate network film. The electron microscopic images supported the formation of the network structure. The high electric conductivity on the network film suggested that the conductive characteristic of the film originated from that of the pi-conjugated polythiophene backbone connected with the gold nanoparticle.

  18. Engineered Gold Nanoparticles and Plant Adaptation Potential

    Science.gov (United States)

    Siddiqi, Khwaja Salahuddin; Husen, Azamal

    2016-09-01

    Use of metal nanoparticles in biological system has recently been recognised although little is known about their possible effects on plant growth and development. Nanoparticles accumulation, translocation, growth response and stress modulation in plant system is not well understood. Plants exposed to gold and gold nanoparticles have been demonstrated to exhibit both positive and negative effects. Their growth and yield vary from species to species. Cytoxicity of engineered gold nanoparticles depends on the concentration, particle size and shape. They exhibit increase in vegetative growth and yield of fruit/seed at lower concentration and decrease them at higher concentration. Studies have shown that the gold nanoparticles exposure has improved free radical scavenging potential and antioxidant enzymatic activities and alter micro RNAs expression that regulate different morphological, physiological and metabolic processes in plants. These modulations lead to improved plant growth and yields. Prior to the use of gold nanoparticles, it has been suggested that its cost may be calculated to see if it is economically feasible.

  19. Subchronic inhalation toxicity of gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Chung Yong

    2011-05-01

    Full Text Available Abstract Background Gold nanoparticles are widely used in consumer products, including cosmetics, food packaging, beverages, toothpaste, automobiles, and lubricants. With this increase in consumer products containing gold nanoparticles, the potential for worker exposure to gold nanoparticles will also increase. Only a few studies have produced data on the in vivo toxicology of gold nanoparticles, meaning that the absorption, distribution, metabolism, and excretion (ADME of gold nanoparticles remain unclear. Results The toxicity of gold nanoparticles was studied in Sprague Dawley rats by inhalation. Seven-week-old rats, weighing approximately 200 g (males and 145 g (females, were divided into 4 groups (10 rats in each group: fresh-air control, low-dose (2.36 × 104 particle/cm3, 0.04 μg/m3, middle-dose (2.36 × 105 particle/cm3, 0.38 μg/m3, and high-dose (1.85 × 106 particle/cm3, 20.02 μg/m3. The animals were exposed to gold nanoparticles (average diameter 4-5 nm for 6 hours/day, 5 days/week, for 90-days in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and lung function 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 organ weights were measured. Cellular differential counts and cytotoxicity measurements, such as albumin, lactate dehydrogenase (LDH, and total protein were also monitored in a cellular bronchoalveolar lavage (BAL fluid. Among lung function test measurements, tidal volume and minute volume showed a tendency to decrease comparing control and dose groups during the 90-days of exposure. Although no statistically significant differences were found in cellular differential counts, histopathologic examination showed minimal alveoli, an inflammatory infiltrate with a mixed cell type, and increased macrophages in the high-dose rats. Tissue

  20. Subchronic inhalation toxicity of gold nanoparticles.

    Science.gov (United States)

    Sung, Jae Hyuck; Ji, Jun Ho; Park, Jung Duck; Song, Moon Yong; Song, Kyung Seuk; Ryu, Hyeon Ryol; Yoon, Jin Uk; Jeon, Ki Soo; Jeong, Jayoung; Han, Beom Seok; Chung, Yong Hyun; Chang, Hee Kyung; Lee, Ji Hyun; Kim, Dong Won; Kelman, Bruce J; Yu, Il Je

    2011-05-14

    Gold nanoparticles are widely used in consumer products, including cosmetics, food packaging, beverages, toothpaste, automobiles, and lubricants. With this increase in consumer products containing gold nanoparticles, the potential for worker exposure to gold nanoparticles will also increase. Only a few studies have produced data on the in vivo toxicology of gold nanoparticles, meaning that the absorption, distribution, metabolism, and excretion (ADME) of gold nanoparticles remain unclear. The toxicity of gold nanoparticles was studied in Sprague Dawley rats by inhalation. Seven-week-old rats, weighing approximately 200 g (males) and 145 g (females), were divided into 4 groups (10 rats in each group): fresh-air control, low-dose (2.36 × 104 particle/cm3, 0.04 μg/m3), middle-dose (2.36 × 105 particle/cm3, 0.38 μg/m3), and high-dose (1.85 × 106 particle/cm3, 20.02 μg/m3). The animals were exposed to gold nanoparticles (average diameter 4-5 nm) for 6 hours/day, 5 days/week, for 90-days in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and lung function 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 organ weights were measured. Cellular differential counts and cytotoxicity measurements, such as albumin, lactate dehydrogenase (LDH), and total protein were also monitored in a cellular bronchoalveolar lavage (BAL) fluid. Among lung function test measurements, tidal volume and minute volume showed a tendency to decrease comparing control and dose groups during the 90-days of exposure. Although no statistically significant differences were found in cellular differential counts, histopathologic examination showed minimal alveoli, an inflammatory infiltrate with a mixed cell type, and increased macrophages in the high-dose rats. Tissue distribution of gold nanoparticles showed a dose

  1. Gold nanoparticle-based electrochemical biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Pingarron, Jose M.; Yanez-Sedeno, Paloma; Gonzalez-Cortes, Araceli [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain)

    2008-08-01

    The unique properties of gold nanoparticles to provide a suitable microenvironment for biomolecules immobilization retaining their biological activity, and to facilitate electron transfer between the immobilized proteins and electrode surfaces, have led to an intensive use of this nanomaterial for the construction of electrochemical biosensors with enhanced analytical performance with respect to other biosensor designs. Recent advances in this field are reviewed in this article. The advantageous operational characteristics of the biosensing devices designed making use of gold nanoparticles are highlighted with respect to non-nanostructured biosensors and some illustrative examples are commented. Electrochemical enzyme biosensors including those using hybrid materials with carbon nanotubes and polymers, sol-gel matrices, and layer-by-layer architectures are considered. Moreover, electrochemical immunosensors in which gold nanoparticles play a crucial role in the electrode transduction enhancement of the affinity reaction as well as in the efficiency of immunoreagents immobilization in a stable mode are reviewed. Similarly, recent advances in the development of DNA biosensors using gold nanoparticles to improve DNA immobilization on electrode surfaces and as suitable labels to improve detection of hybridization events are considered. Finally, other biosensors designed with gold nanoparticles oriented to electrically contact redox enzymes to electrodes by a reconstitution process and to the study of direct electron transfer between redox proteins and electrode surfaces have also been treated. (author)

  2. Accumulation of Gold Nanoparticles in Brassic Juncea

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, A.T.; Haverkamp, R.G.; Davies, C.E.; Parsons, J.G.; Gardea-Torresdey, J.L.; Agterveld, D.van

    2009-06-03

    Enzymatic digestion is proposed as a method for concentrating gold nanoparticles produced in plants. The mild conditions of digestion are used in order to avoid an increase in the gold particle size, which would occur with a high-temperature process, so that material suitable for catalysis may be produced. Gold nanoparticles of a 5-50-nm diameter, as revealed by transmission electron microscopy (TEM), at concentrations 760 and 1120 ppm Au, were produced within Brassica juncea grown on soil with 22-48 mg Au kg{sup -1}. X-ray absorption near edge spectroscopy (XANES) reveals that the plant contained approximately equal quantities of Au in the metallic (Au{sup 0}) and oxidized (Au{sup +1}) states. Enzymatic digestion dissolved 55-60 wt% of the plant matter. Due to the loss of the soluble gold fraction, no significant increase in the total concentration of gold in the samples was observed. However, it is likely that the concentration of the gold nanoparticles increased by a factor of two. To obtain a gold concentration suitable for catalytic reactions, around 95 wt% of the starting dry biomass would need to be solubilized or removed, which has not yet been achieved.

  3. Accumulation of gold nanoparticles in Brassic juncea.

    Science.gov (United States)

    Marshall, Aaron T; Haverkamp, Richard G; Davies, Clive E; Parsons, Jason G; Gardea-Torresdey, Jorge L; van Agterveld, Dimitri

    2007-01-01

    Enzymatic digestion is proposed as a method for concentrating gold nanoparticles produced in plants. The mild conditions of digestion are used in order to avoid an increase in the gold particle size, which would occur with a high-temperature process, so that material suitable for catalysis may be produced. Gold nanoparticles of a 5-50-nm diameter, as revealed by transmission electron microscopy (TEM), at concentrations 760 and 1120 ppm Au, were produced within Brassica juncea grown on soil with 22-48 mg Au kg(-1). X-ray absorption near edge spectroscopy (XANES) reveals that the plant contained approximately equal quantities of Au in the metallic (Au0) and oxidized (Au+1) states. Enzymatic digestion dissolved 55-60 wt% of the plant matter. Due to the loss of the soluble gold fraction, no significant increase in the total concentration of gold in the samples was observed. However, it is likely that the concentration of the gold nanoparticles increased by a factor of two. To obtain a gold concentration suitable for catalytic reactions, around 95 wt% of the starting dry biomass would need to be solubilized or removed, which has not yet been achieved.

  4. Polymer decorated gold nanoparticles in nanomedicine conjugates.

    Science.gov (United States)

    Capek, Ignác

    2017-02-15

    Noble metal, especially gold nanoparticles and their conjugates with biopolymers have immense potential for disease diagnosis and therapy on account of their surface plasmon resonance (SPR) enhanced light scattering and absorption. Conjugation of noble metal nanoparticles to ligands specifically targeted to biomarkers on diseased cells allows molecular-specific imaging and detection of disease. The development of smart gold nanoparticles (AuNPs) that can deliver therapeutics at a sustained rate directly to cancer cells may provide better efficacy and lower toxicity for treating cancer tumors. We highlight some of the promising classes of targeting systems that are under development for the delivery of gold nanoparticles. Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups to conjugate targeting ligands, cell receptors or drugs. Using targeted nanoparticles to deliver chemotherapeutic agents in cancer therapy offers many advantages to improve drug/gene delivery and to overcome many problems associated with conventional radiotherapy and chemotherapy. The targeted nanoparticles were found to be effective in killing cancer cells which were studied using various anticancer assays. Cell morphological analysis shows the changes occurred in cancer cells during the treatment with AuNPs. The results determine the influence of particle size and concentration of AuNPs on their absorption, accumulation, and cytotoxicity in model normal and cancer cells. As the mean particle diameter of the AuNPs decreased, their rate of absorption by the intestinal epithelium cells increased. These results provide important insights into the relationship between the dimensions of AuNPs and their gastrointestinal uptake and potential cytotoxicity. Furthermore gold nanoparticles efficiently convert the absorbed light into localized heat, which can be exploited for the selective laser photothermal therapy of cancer. We also review

  5. Irradiation stability and cytotoxicity of gold nanoparticles for radiotherapy

    OpenAIRE

    Zhang, Xiao-Dong; Guo, Mei-Li; Wu, Hong-Ying; Sun, Yuan-Ming; Ding, Yan-Qiu; Feng, Xin; Zhang, Liang-An

    2009-01-01

    Gold nanoparticles are promising as a kind of novel radiosensitizer in radiotherapy. If gold nanoparticles are shown to have good irradiation stability and biocompatibility, they would play an important role in radiotherapy. In this work, we investigated irradiation effects of gold nanoparticles under 2–10 kR gamma irradiation and cytotoxicity of gold nanoparticles with human K562 cells by using Cell Titre-Glo™ luminescent cell viability assay. The results revealed that gamma irradiation had ...

  6. Biosynthesis of gold nanoparticles: A green approach.

    Science.gov (United States)

    Ahmed, Shakeel; Annu; Ikram, Saiqa; Yudha S, Salprima

    2016-08-01

    Nanotechnology is an immensely developing field due to its extensive range of applications in different areas of technology and science. Different types of methods are employed for synthesis of nanoparticles due to their wide applications. The conventional chemical methods have certain limitations with them either in the form of chemical contaminations during their syntheses procedures or in later applications and use of higher energy. During the last decade research have been focussed on developing simple, clean, non-toxic, cost effective and eco-friendly protocols for synthesis of nanoparticles. In order to get this objective, biosynthesis methods have been developed in order to fill this gap. The biosynthesis of nanoparticles is simple, single step, eco-friendly and a green approach. The biochemical processes in biological agents reduce the dissolved metal ions into nano metals. The various biological agents like plant tissues, fungi, bacteria, etc. are used for biosynthesis for metal nanoparticles. In this review article, we summarised recent literature on biosynthesis of gold nanoparticles which have revolutionised technique of synthesis for their applications in different fields. Due to biocompatibility of gold nanoparticles, it has find its applications in biomedical applications. The protocol and mechanism of biosynthesis of gold nanoparticles along with various applications have also been discussed.

  7. Titration of gold nanoparticles in phase extraction.

    Science.gov (United States)

    Cheng, Han-Wen; Schadt, Mark J; Zhong, Chuan-Jian

    2015-12-07

    In the organic-aqueous phase transfer process of gold nanoparticles, there are two types of distinctive interfaces involving hydrophilic and hydrophobic ligands, the understanding of which is important for the design of functional nanomaterials for analytical/bioanalytical applications and the control over the nanoparticles' nanoactivity and nanotoxicity in different phases. This report describes new findings of an investigation of the quantitative aspect of ligand ion pairing at the capping monolayer structure that drives the phase extraction of gold nanoparticles. Alkanethiolate-capped gold nanoparticles of 8 nm diameter with high size monodispersity (RSD ∼ 5%) were first derivatized by a ligand place exchange reaction with 11-mercaptoundecanoic acid to form a mixed monolayer shell consisting of both hydrophobic (-CH3) and hydrophilic (-COOH) groups. It was followed by quantitative titration of the resulting nanoparticles with a cationic species (-NR4(+)) in a toluene phase, yielding ion pairing of -NR4(+) and -COO(-) on part of the capping monolayer. Analysis of the phase extraction allowed a quantitative determination of the percentage of ion pairing and structural changes in the capping monolayer on the nanoparticles. The results, along with morphological characterization, are discussed in terms of the interfacial structural changes and their implications on the rational design of surface-functionalized nanoparticles and fine tuning of the interfacial reactivity.

  8. Optical Epitaxial Growth of Gold Nanoparticle Arrays.

    Science.gov (United States)

    Huang, Ningfeng; Martínez, Luis Javier; Jaquay, Eric; Nakano, Aiichiro; Povinelli, Michelle L

    2015-09-09

    We use an optical analogue of epitaxial growth to assemble gold nanoparticles into 2D arrays. Particles are attracted to a growth template via optical forces and interact through optical binding. Competition between effects determines the final particle arrangements. We use a Monte Carlo model to design a template that favors growth of hexagonal particle arrays. We experimentally demonstrate growth of a highly stable array of 50 gold particles with 200 nm diameter, spaced by 1.1 μm.

  9. Photoluminescence of hollow gold-silver bimetallic nanoparticles

    OpenAIRE

    Weon-Sik Chae; Hee-Ok Lee; Seung-Lim Oh

    2011-01-01

    Hollow gold nanoparticles including silver were prepared by the galvanic replacement reaction of silver nanoparticles by gold. The resulting hollow gold-silver bimetallic nanoparticles show notable blue-green emissions, which are studied using steady-state and time-resolved spectroscopy.

  10. Photoluminescence of hollow gold-silver bimetallic nanoparticles

    Directory of Open Access Journals (Sweden)

    Weon-Sik Chae

    2011-12-01

    Full Text Available Hollow gold nanoparticles including silver were prepared by the galvanic replacement reaction of silver nanoparticles by gold. The resulting hollow gold-silver bimetallic nanoparticles show notable blue-green emissions, which are studied using steady-state and time-resolved spectroscopy.

  11. Gold-coated nanoparticles for use in biotechnology applications

    Science.gov (United States)

    Berning, Douglas E.; Kraus, Jr., Robert H.; Atcher, Robert W.; Schmidt, Jurgen G.

    2007-06-05

    A process of preparing gold-coated magnetic nanoparticles is disclosed and includes forming a suspension of magnetic nanoparticles within a suitable liquid, adding an amount of a reducible gold compound and a reducing agent to the suspension, and, maintaining the suspension for time sufficient to form gold-coated magnetic nanoparticles.

  12. Ordered arrays of nanoporous gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2012-09-01

    Full Text Available A combination of a “top-down” approach (substrate-conformal imprint lithography and two “bottom-up” approaches (dewetting and dealloying enables fabrication of perfectly ordered 2-dimensional arrays of nanoporous gold nanoparticles. The dewetting of Au/Ag bilayers on the periodically prepatterned substrates leads to the interdiffusion of Au and Ag and the formation of an array of Au–Ag alloy nanoparticles. The array of alloy nanoparticles is transformed into an array of nanoporous gold nanoparticles by a following dealloying step. Large areas of this new type of material arrangement can be realized with this technique. In addition, this technique allows for the control of particle size, particle spacing, and ligament size (or pore size by varying the period of the structure, total metal layer thickness, and the thickness ratio of the as-deposited bilayers.

  13. Optical Trapping of Gold Nanoparticles in Air.

    Science.gov (United States)

    Jauffred, Liselotte; Taheri, S Mohammad-Reza; Schmitt, Regina; Linke, Heiner; Oddershede, Lene B

    2015-07-08

    Most progress on optical nanoparticle control has been in liquids, while optical control in air has proven more challenging. By utilizing an air chamber designed to have a minimum of turbulence and a single laser beam with a minimum of aberration, we trapped individual 200 to 80 nm gold nanoparticles in air and quantified the corresponding trapping strengths. These results pave the way for construction of metallic nanostructures in air away from surfaces.

  14. Applications of gold nanoparticles in cancer nanotechnology

    Directory of Open Access Journals (Sweden)

    Weibo Cai

    2008-09-01

    Full Text Available Weibo Cai1,2, Ting Gao3, Hao Hong1, Jiangtao Sun11Departments of Radiology and Medical Physics, School of Medicine and Public Health, University of Wisconsin – Madison, Madison, Wisconsin, USA; 2University of Wisconsin Paul P. Carbone Comprehensive Cancer Center, Madison, Wisconsin, USA; 3Tyco Electronics Corporation, 306 Constitution Drive, Menlo Park, California, USAAbstract: It has been almost 4 decades since the “war on cancer” was declared. It is now generally believed that personalized medicine is the future for cancer patient management. Possessing unprecedented potential for early detection, accurate diagnosis, and personalized treatment of cancer, nanoparticles have been extensively studied over the last decade. In this review, we will summarize the current state-of-the-art of gold nanoparticles in biomedical applications targeting cancer. Gold nanospheres, nanorods, nanoshells, nanocages, and surface enhanced Raman scattering nanoparticles will be discussed in detail regarding their uses in in vitro assays, ex vivo and in vivo imaging, cancer therapy, and drug delivery. Multifunctionality is the key feature of nanoparticle-based agents. Targeting ligands, imaging labels, therapeutic drugs, and other functionalities can all be integrated to allow for targeted molecular imaging and molecular therapy of cancer. Big strides have been made and many proof-of-principle studies have been successfully performed. The future looks brighter than ever yet many hurdles remain to be conquered. A multifunctional platform based on gold nanoparticles, with multiple receptor targeting, multimodality imaging, and multiple therapeutic entities, holds the promise for a “magic gold bullet” against cancer.Keywords: gold nanoparticles, cancer, nanotechnology, optical imaging, nanomedicine, molecular therapy

  15. Plasmonic biocompatible silver-gold alloyed nanoparticles.

    Science.gov (United States)

    Sotiriou, Georgios A; Etterlin, Gion Diego; Spyrogianni, Anastasia; Krumeich, Frank; Leroux, Jean-Christophe; Pratsinis, Sotiris E

    2014-11-14

    The addition of Au during scalable synthesis of nanosilver drastically minimizes its surface oxidation and leaching of toxic Ag(+) ions. These biocompatible and inexpensive silver-gold nanoalloyed particles exhibit superior plasmonic performance than commonly used pure Au nanoparticles, and as such these nanoalloys have great potential in theranostic applications.

  16. Surface interactions between gold nanoparticles and biochar

    Science.gov (United States)

    Engineered nanomaterials are directly applied to agricultural soils as a part of pesticide/fertilize formulations and sludge/manure amendments. Yet, no prior reports are available on the extent and reversibility of gold nanoparticles (nAu) retention by soil components including charcoal black carbo...

  17. Protracted elimination of gold nanoparticles from mouse liver

    DEFF Research Database (Denmark)

    Sadauskas, Evaldas; Wallin, Håkan; Stoltenberg, Meredin

    2009-01-01

    The present study aims at revealing the fate of 40-nm gold nanoparticles after intravenous injections. The gold nanoparticles were traced histochemically with light and transmission electron microscopy using autometallographic (AMG) staining, and the gold content in the liver was determined...... with inductively coupled plasma mass spectrometry (ICP-MS). Gold nanoparticles were identified in almost all Kupffer cells one day after the injection, but the fraction of gold-loaded cells gradually decreased to about one fifth after 6 months. Transmission electron microscopic analysis showed that the gold......% fall in the gold content over the observed 6 months, the AMG finding of a significant reduction in the stained area of the liver sections and number of macrophages loaded with gold nanoparticles reveals that over time an increasing part of the total amount of gold nanoparticles in the liver...

  18. Antifungal activity of gold nanoparticles prepared by solvothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Manzoor, Nikhat; Ahmad, Aijaz [Department of Biosciences, Jamia Millia Islamia, New Delhi 110025 (India); Ahmed, Jahangeer [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Al-Shihri, Ayed S. [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia)

    2013-01-15

    Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m{sup 2/}g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.

  19. Gold nanoparticle (AuNPs) and gold nanopore (AuNPore) catalysts in organic synthesis.

    Science.gov (United States)

    Takale, Balaram S; Bao, Ming; Yamamoto, Yoshinori

    2014-04-07

    Organic synthesis using gold has gained tremendous attention in last few years, especially heterogeneous gold catalysis based on gold nanoparticles has made its place in almost all organic reactions, because of the robust and green nature of gold catalysts. In this context, gold nanopore (AuNPore) with a 3D metal framework is giving a new dimension to heterogeneous gold catalysts. Interestingly, AuNPore chemistry is proving better than gold nanoparticles based chemistry. In this review, along with recent advances, major discoveries in heterogeneous gold catalysis are discussed.

  20. Photothermal fluctuation spectroscopy on gold nanoparticle dimers

    Energy Technology Data Exchange (ETDEWEB)

    Waehnert, Miriam; Neubauer, Nils; Raduenz, Romy; Cichos, Frank [Molecular Nanophotonics Group, University of Leipzig, Linnestrasse 5, 04103 Leipzig (Germany)

    2009-07-01

    To measure distance changes on the nanoscale, FRET (Fluorescence resonance energy transfer) is a heavily applied technique in biophysical studies. The upper limit of distance fluctuations being measured with this method is about 10 nm. Furthermore it suffers from photochemical degradation mechanisms like blinking and bleaching of the energy transferring dye molecules. We report on recent experiments using pairs of gold nanoparticles as absorbing markers replacing dye molecules. Gold particles are strongly interacting with light, if they are excited near the plasmon resonance. The resulting dipoles of two closely spaced gold nanoparticles can couple to form a new resonance, which appears in the absorption as a distinct feature. The strength of this absorption depends on the distance of the two particles and is visible up to a few 10 nm, which clearly exceeds the lengthscale of FRET. The gold nanoparticles are detected by photothermal heterodyne detection, using the release of heat from the absorbing particles to create a local refractive index change around them, which can be probed with a confocal laser scanning setup. Due to the plasmon coupling a fluctuating distance will result in a fluctuating photothermal signal. Numerical analyses of the spectra together with first experimental results will be presented.

  1. Gold Nanoparticle-Biological Molecule Interactions and Catalysis

    Directory of Open Access Journals (Sweden)

    Jonathan G. Heddle

    2013-09-01

    Full Text Available This review gives a brief summary of the field of gold nanoparticle interactions with biological molecules, particularly those with possible catalytic relevance. Gold nanoparticles are well known as catalysts in organic chemistry but much is unknown regarding their potential as catalysts of reactions involving biological molecules such as protein and nucleic acids. Biological molecules may be the substrate for catalysis or, if they are the ligand coating the gold particle, may be the catalyst itself. In other cases biological molecules may form a template upon which gold nanoparticles can be precisely arrayed. As relatively little is currently known about the catalytic capabilities of gold nanoparticles in this area, this review will consider templating in general (including, but not restricted to, those which result in structures having potential as catalysts before going on to consider firstly catalysis by the gold nanoparticle itself followed by catalysis by ligands attached to gold nanoparticles, all considered with a focus on biological molecules.

  2. X-ray optics of gold nanoparticles.

    Science.gov (United States)

    Letfullin, Renat R; Rice, Colin E W; George, Thomas F

    2014-11-01

    Gold nanoparticles have been investigated as contrast agents for traditional x-ray medical procedures, utilizing the strong absorption characteristics of the nanoparticles to enhance the contrast of the detected x-ray image. Here we use the Kramers-Kronig relation for complex atomic scattering factors to find the real and imaginary parts of the index of refraction for the medium composed of single-element materials or compounds in the x-ray range of the spectrum. These complex index of refraction values are then plugged into a Lorenz-Mie theory to calculate the absorption efficiency of various size gold nanoparticles for photon energies in the 1-100 keV range. Since the output from most medical diagnostic x-ray devices follows a wide and filtered spectrum of photon energies, we introduce and compute the effective intensity-absorption-efficiency values for gold nanoparticles of radii varying from 5 to 50 nm, where we use the TASMIP model to integrate over all spectral energies generated by typical tungsten anode x-ray tubes with kilovolt potentials ranging from 50 to 150 kVp.

  3. Controlled synthesis and optical properties of pure gold nanoparticles

    NARCIS (Netherlands)

    Singh, A.K.; Rai, A.K.; Bicanic, D.D.

    2009-01-01

    Gold nanoparticles were synthesized by laser ablation of a gold metallic disc at wavelengths of 532 nm and 355 nm with 7 ns pulse duration in the pure water. The colloidal gold nanoparticles were characterized by ultraviolet-visible absorption spectroscopy, transmission electron microscopy, and

  4. Controlled synthesis and optical properties of pure gold nanoparticles

    NARCIS (Netherlands)

    Singh, A.K.; Rai, A.K.; Bicanic, D.D.

    2009-01-01

    Gold nanoparticles were synthesized by laser ablation of a gold metallic disc at wavelengths of 532 nm and 355 nm with 7 ns pulse duration in the pure water. The colloidal gold nanoparticles were characterized by ultraviolet-visible absorption spectroscopy, transmission electron microscopy, and fluo

  5. Gold nanoparticles: preparation, functionalisation and applications in biochemistry and immunochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Dykman, Lev A; Bogatyrev, Vladimir A [Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences (Russian Federation)

    2007-02-28

    The review summarises data on the synthesis and functionalisation of gold nanoparticles and their applications in biological investigations. Particular attention is given to applications of colloidal gold in solid-phase assays, immunoassay and studies of biologically active compounds by vibrational spectroscopy. A special section deals with the use of gold nanoparticles as antigen carriers in immunisation.

  6. Synthesis of gold nanoparticles using various amino acids.

    Science.gov (United States)

    Maruyama, Tatsuo; Fujimoto, Yuhei; Maekawa, Tetsuya

    2015-06-01

    Gold nanoparticles (4-7nm) were synthesized from tetraauric acid using various amino acids as reducing and capping agents. The gold nanoparticles were produced from the incubation of a AuCl4(-) solution with an amino acid at 80°C for 20min. Among the twenty amino acids tested, several amino acids produced gold nanoparticles. The color of the nanoparticle solutions varied with the amino acids used for the reduction. We adopted l-histidine as a reducing agent and investigated the effects of the synthesis conditions on the gold nanoparticles. The His and AuCl4(-) concentrations affected the size of the gold nanoparticles and their aggregates. The pH of the reaction solution also affected the reaction yields and the shape of the gold nanoparticles.

  7. Monofunctional gold nanoparticles: synthesis and applications

    Science.gov (United States)

    Huo, Qun; Worden, James G.

    2007-12-01

    The ability to control the assembly of nanoparticle building blocks is critically important for the development of new materials and devices. The properties and functions of nanomaterials are not only dependent on the size and properties of individual particles, but also the interparticle distance and interactions. In order to control the structures of nanoassemblies, it is important to first achieve a precise control on the chemical functionality of nanoparticle building blocks. This review discusses three methods that have been reported recently for the preparation of monofunctional gold nanoparticles, i.e., nanoparticles with a single chemical functional group attached to each particle. The advantages and disadvantages of the three methods are discussed and compared. With a single functional group attached to the surface, one can treat such nanoparticles as molecular building blocks to react with other molecules or nanoparticles. In other words, by using appropriate chemical reactions, nanoparticles can be linked together into nanoassemblies and materials by covalent bonds, similar to the total chemical synthesis of complicated organic compounds from smaller molecular units. An example of using this approach for the synthesis of nanoparticle/polymer hybrid materials with optical limiting properties is presented. Other potential applications and advantages of covalent bond-based nanoarchitectures vs. non-covalent interaction-based supramolecular self-assemblies are also discussed briefly in this review.

  8. Monofunctional gold nanoparticles: synthesis and applications

    Energy Technology Data Exchange (ETDEWEB)

    Huo Qun, E-mail: qhuo@mail.ucf.edu; Worden, James G. [University of Central Florida, Nanoscience Technology Center and the Department of Chemistry (United States)

    2007-12-15

    The ability to control the assembly of nanoparticle building blocks is critically important for the development of new materials and devices. The properties and functions of nanomaterials are not only dependent on the size and properties of individual particles, but also the interparticle distance and interactions. In order to control the structures of nanoassemblies, it is important to first achieve a precise control on the chemical functionality of nanoparticle building blocks. This review discusses three methods that have been reported recently for the preparation of monofunctional gold nanoparticles, i.e., nanoparticles with a single chemical functional group attached to each particle. The advantages and disadvantages of the three methods are discussed and compared. With a single functional group attached to the surface, one can treat such nanoparticles as molecular building blocks to react with other molecules or nanoparticles. In other words, by using appropriate chemical reactions, nanoparticles can be linked together into nanoassemblies and materials by covalent bonds, similar to the total chemical synthesis of complicated organic compounds from smaller molecular units. An example of using this approach for the synthesis of nanoparticle/polymer hybrid materials with optical limiting properties is presented. Other potential applications and advantages of covalent bond-based nanoarchitectures vs. non-covalent interaction-based supramolecular self-assemblies are also discussed briefly in this review.

  9. Terminalia chebula mediated green and rapid synthesis of gold nanoparticles.

    Science.gov (United States)

    Kumar, Kesarla Mohan; Mandal, Badal Kumar; Sinha, Madhulika; Krishnakumar, Varadhan

    2012-02-01

    Biologically inspired experimental process in synthesising nanoparticles is of great interest in present scenario. Biosynthesis of nanoparticles is considered to be one of the best green techniques in synthesising metal nanoparticles. Here, an in situ green biogenic synthesis of gold nanoparticles using aqueous extracts of Terminalia chebula as reducing and stabilizing agent is reported. Gold nanoparticles were confirmed by surface plasmon resonance in the range of 535 nm using UV-visible spectrometry. TEM analysis revealed that the morphology of the particles thus formed contains anisotropic gold nanoparticles with size ranging from 6 to 60 nm. Hydrolysable tannins present in the extract of T. chebula are responsible for reductions and stabilization of gold nanoparticles. Antimicrobial activity of gold nanoparticles showed better activity towards gram positive S. aureus compared to gram negative E. coli using standard well diffusion method.

  10. Immobilization of gold nanoparticles on cell culture surfaces for safe and enhanced gold nanoparticle-mediated laser transfection

    Science.gov (United States)

    Kalies, Stefan; Heinemann, Dag; Schomaker, Markus; Gentemann, Lara; Meyer, Heiko; Ripken, Tammo

    2014-07-01

    In comparison to standard transfection methods, gold nanoparticle-mediated laser transfection has proven to be a versatile alternative. This is based on its minor influence on cell viability and its high efficiency, especially for the delivery of small molecules like small interfering RNA. However, in order to transfer it to routine usage, a safety aspect is of major concern: The avoidance of nanoparticle uptake by the cells is desired. The immobilization of the gold nanoparticles on cell culture surfaces can address this issue. In this study, we achieved this by silanization of the appropriate surfaces and the binding of gold nanoparticles to them. Comparable perforation efficiencies to the previous approaches of gold nanoparticle-mediated laser transfection with free gold nanoparticles are demonstrated. The uptake of the immobilized particles by the cells is unlikely. Consequently, these investigations offer the possibility of bringing gold nanoparticle-mediated laser transfection closer to routine usage.

  11. Immobilization of gold nanoparticles on cell culture surfaces for safe and enhanced gold nanoparticle-mediated laser transfection.

    Science.gov (United States)

    Kalies, Stefan; Heinemann, Dag; Schomaker, Markus; Gentemann, Lara; Meyer, Heiko; Ripken, Tammo

    2014-01-01

    In comparison to standard transfection methods, gold nanoparticle-mediated laser transfection has proven to be a versatile alternative. This is based on its minor influence on cell viability and its high efficiency, especially for the delivery of small molecules like small interfering RNA. However, in order to transfer it to routine usage, a safety aspect is of major concern: The avoidance of nanoparticle uptake by the cells is desired. The immobilization of the gold nanoparticles on cell culture surfaces can address this issue. In this study, we achieved this by silanization of the appropriate surfaces and the binding of gold nanoparticles to them. Comparable perforation efficiencies to the previous approaches of gold nanoparticle-mediated laser transfection with free gold nanoparticles are demonstrated. The uptake of the immobilized particles by the cells is unlikely. Consequently, these investigations offer the possibility of bringing gold nanoparticle-mediated laser transfection closer to routine usage.

  12. GOLD NANOPARTICLES: PROMISING AND POTENTIAL NANOMATERIAL

    Directory of Open Access Journals (Sweden)

    Madhuri Shringirishi*, S.K. Prajapati , Alok Mahor , Shashi Alok , Poonam Yadav and Amita Verma

    2013-11-01

    Full Text Available Gold nanoparticles (AuNPs have appeared as an attractive candidate for delivery of various drug molecules or considered as extraordinary molecular carriers for the targeting, intracellular trafficking and delivery of a huge array of biomolecules including DNA, RNA, proteins, peptides, drugs, genes and other molecules of therapeutic significance. Particularly gold nanoparticles have attracted intensive interest, because they are easily prepared, have low toxicity and can be readily attached to molecules of biological interest. More and more research shows that AuNPs-based technologies are becoming promising approaches in drug and gene delivery, liver targeting, brain targeting, cancer research and AIDS treatment. The present review focuses on synthesis and functionalization methods of GNPs, the past researchs and reviews about GNPs, their emerging applications and uses and their future prospects.

  13. Attachment of Gold Nanoparticles to Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xi Cheng MA; Ning LUN; Shu Lin WEN

    2005-01-01

    Carbon nanotubes were initially chemically modified with an H2SO4-HNO3 treatment,and subsequently activated with Pd-Sn catalytic nuclei via a one-step activation approach. These activated nanotubes were used as precursors for obtaining gold nanoparticles-attached nanotubes via simple electroless plating. This approach provides an efficient method for attachment of metal nanostructures to carbon nanotubes. Such novel hybrid nanostructures are attractive for many applications.

  14. Optical Limiting Materials Based on Gold Nanoparticles

    Science.gov (United States)

    2014-04-30

    Murphy, University of Illinois at Urbana-Champaign (formerly University of South Carolina), Department of Chemistry Award Number: FA9550-09-1-0246...of the electromagnetic spectrum. 2. Functionalization of the surface of the gold nanoparticles with selected organic and inorganic materials, with...the thesis work of one Ph.D. student (Sean Sivapalan, Ph.D. in materials science and engineering, graduated in 2013, now employed at Intel

  15. Shape-Controlled Gold Nanoparticle Synthesis

    Science.gov (United States)

    2013-09-01

    prisms (5, 13–17), nanospheres (18, 19), and other platonic (20–22), branched (12), and anisotropic (12, 23, 24) morphologies. Although synthesis...polyol reaction method involving the use of poly(vinylpyrrolidone) as a reducing agent to produce various platonic Au nanoparticles. In a very...6786. 20. Kim, F.; Connor, S.; Song, H.; Kuykendall, T.; Yang, P. Platonic Gold Nanocrystals. Angewandte Chemie International Edition 2004, 43

  16. Microbial synthesis of gold nanoparticles: current status and future prospects.

    Science.gov (United States)

    Shedbalkar, Utkarsha; Singh, Richa; Wadhwani, Sweety; Gaidhani, Sharvari; Chopade, B A

    2014-07-01

    Gold nanoparticles have been employed in biomedicine since the last decade because of their unique optical, electrical and photothermal properties. Present review discusses the microbial synthesis, properties and biomedical applications of gold nanoparticles. Different microbial synthesis strategies used so far for obtaining better yield and stability have been described. It also includes different methods used for the characterization and analysis of gold nanoparticles, viz. UV-visible spectroscopy, Fourier transform infrared spectroscopy, X ray diffraction spectroscopy, scanning electron microscopy, ransmission electron microscopy, atomic force microscopy, electron dispersive X ray, X ray photoelectron spectroscopy and cyclic voltametry. The different mechanisms involved in microbial synthesis of gold nanoparticles have been discussed. The information related to applications of microbially synthesized gold nanoparticles and patents on microbial synthesis of gold nanoparticles has been summarized.

  17. Detection of squamous carcinoma cells using gold nanoparticles

    Science.gov (United States)

    Dai, Wei-Yun; Lee, Sze-tsen; Hsu, Yih-Chih

    2015-03-01

    The goal of this study is to use gold nanoparticle as a diagnostic agent to detect human squamous carcinoma cells. Gold nanoparticles were synthesized and the gold nanoparticle size was 34.3 ± 6.2 nm. Based on the over-expression of epidermal growth factor receptor (EGFR) biomarkers in squamous carcinoma cells, we hypothesized that EGFR could be a feasible biomarker with a target moiety for detection. We further modified polyclonal antibodies of EGFR on the surface of gold nanoparticles. We found selected squamous carcinoma cells can be selectively detected using EGFR antibody-modified gold nanoparticles via receptor-mediated endocytosis. Cell death was also examined to determine the survival status of squamous carcinoma cells with respect to gold nanoparticle treatment and EGFR polyclonal antibody modification.

  18. Plasmonic photothermal therapy (PPTT) using gold nanoparticles.

    Science.gov (United States)

    Huang, Xiaohua; Jain, Prashant K; El-Sayed, Ivan H; El-Sayed, Mostafa A

    2008-07-01

    The use of lasers, over the past few decades, has emerged to be highly promising for cancer therapy modalities, most commonly the photothermal therapy method, which employs light absorbing dyes for achieving the photothermal damage of tumors, and the photodynamic therapy, which employs chemical photosensitizers that generate singlet oxygen that is capable of tumor destruction. However, recent advances in the field of nanoscience have seen the emergence of noble metal nanostructures with unique photophysical properties, well suited for applications in cancer phototherapy. Noble metal nanoparticles, on account of the phenomenon of surface plasmon resonance, possess strongly enhanced visible and near-infrared light absorption, several orders of magnitude more intense compared to conventional laser phototherapy agents. The use of plasmonic nanoparticles as highly enhanced photoabsorbing agents has thus introduced a much more selective and efficient cancer therapy strategy, viz. plasmonic photothermal therapy (PPTT). The synthetic tunability of the optothermal properties and the bio-targeting abilities of the plasmonic gold nanostructures make the PPTT method furthermore promising. In this review, we discuss the development of the PPTT method with special emphasis on the recent in vitro and in vivo success using gold nanospheres coupled with visible lasers and gold nanorods and silica-gold nanoshells coupled with near-infrared lasers.

  19. Gold nanoparticles as novel agents for cancer therapy.

    Science.gov (United States)

    Jain, S; Hirst, D G; O'Sullivan, J M

    2012-02-01

    Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. This review introduces the field of nanotechnology with a focus on recent gold nanoparticle research which has led to early-phase clinical trials. In particular, the pre-clinical evidence for gold nanoparticles as sensitisers with ionising radiation in vitro and in vivo at kilovoltage and megavoltage energies is discussed.

  20. Preparation and characterization of graphene oxide encapsulated gold nanoparticles.

    Science.gov (United States)

    Yun, Yong Ju; Song, Ki-Bong

    2013-11-01

    We present a simple approach for the fabrication of graphene oxide-encapsulated gold nanoparticles using graphene oxide sheet-wrapping via electrostatic self-assembly. By mixing bovine serum albumin molecule-functionalized gold nanoparticles with graphene oxide dispersion, positively charged bovine serum albumin/gold nanoparticles easily assembled with negatively charged graphene oxide sheets through electrostatic interaction. Transmittance electron microscopy, scanning electron microscopy, atomic force microscopy, and Raman spectroscopy were used to confirm the encapsulation of graphene oxide on gold nanoparticles. Interestingly, graphene oxide sheets wrapping mainly occurs along the main body of single or a few gold nanoparticles. Additionally, by measuring the ultraviolet-visible spectroscopy spectrum, we found that the surface plasmon resonances band of the graphene oxide-encapsulated gold nanoparticles was found to become red-shifted compared to that of pristine gold nanoparticles, whereas similar to that of bovine serum albumin-coated gold nanoparticles. These results indicating that most of graphene oxide-encapsulated gold nanoparticles have good monodispersity and spherical shape. These resulting materials may potentially serve as a platform for plasmon resonance electron transfer spectroscopy or a probe for low level biosensing.

  1. Methanobactin-mediated one-step synthesis of gold nanoparticles.

    Science.gov (United States)

    Xin, Jia-ying; Cheng, Dan-dan; Zhang, Lan-xuan; Lin, Kai; Fan, Hong-chen; Wang, Yan; Xia, Chun-gu

    2013-11-01

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

  2. Methanobactin-Mediated One-Step Synthesis of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yan Wang

    2013-11-01

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

  3. Damping of acoustic vibrations in gold nanoparticles

    Science.gov (United States)

    Pelton, Matthew; Sader, John E.; Burgin, Julien; Liu, Mingzhao; Guyot-Sionnest, Philippe; Gosztola, David

    2009-08-01

    Studies of acoustic vibrations in nanometre-scale particles can provide fundamental insights into the mechanical properties of materials because it is possible to precisely characterize and control the crystallinity and geometry of such nanostructures. Metal nanoparticles are of particular interest because they allow the use of ultrafast laser pulses to generate and probe high-frequency acoustic vibrations, which have the potential to be used in a variety of sensing applications. So far, the decay of these vibrations has been dominated by dephasing due to variations in nanoparticle size. Such inhomogeneities can be eliminated by performing measurements on single nanoparticles deposited on a substrate, but unknown interactions between the nanoparticles and the substrate make it difficult to interpret the results of such experiments. Here, we show that the effects of inhomogeneous damping can be reduced by using bipyramidal gold nanoparticles with highly uniform sizes. The inferred homogeneous damping is due to the combination of damping intrinsic to the nanoparticles and the surrounding solvent; the latter is quantitatively described by a parameter-free model.

  4. Ultrasonic alloying of preformed gold and silver nanoparticles.

    Science.gov (United States)

    Radziuk, Darya V; Zhang, Wei; Shchukin, Dmitry; Möhwald, Helmuth

    2010-02-22

    Alloyed gold/silver nanoparticles with a core/shell structure are produced from preformed gold and silver nanoparticles during ultrasonic treatment at different intensities in water and in the presence of surface-active species. Preformed gold nanoparticles with an average diameter of 15 + or - 5 nm are prepared by the citrate reduction of chloroauric acid in water, and silver nanoparticles (38 + or - 7 nm) are formed after reduction of silver nitrate by sodium borohydride. Bare binary gold/silver nanoparticles with a core/shell structure are formed in aqueous solution after 1 h of sonication at high ultrasonic intensity. Cationic-surfactant-coated preformed gold and silver nanoparticles become gold/silver-alloy nanoparticles after 3 h of sonication in water at 55 W cm(-2), whereas only fusion of isolated gold and silver nanoparticles is observed after ultrasonic treatment in the presence of an anionic surfactant. As the X-ray diffraction profile of alloyed gold/silver nanoparticles reveals split, shifted, and disappeared peaks, the face-centered-cubic crystalline structure of the binary nanoparticles is defect-enriched by temperatures that can be as high as several thousand Kelvin inside the cavitation bubbles during ultrasonic treatment.

  5. Facially amphiphilic thiol capped gold and silver nanoparticles

    Indian Academy of Sciences (India)

    Shreedhar Bhata; Uday Maitra

    2008-11-01

    A series of bile acid-derived facially amphiphilic thiols have been used to cap sliver and gold nanoparticles. The self-assembling properties of these steroid-capped nanoparticles have been investigated and reported in this article.

  6. Microbial biosynthesis of nontoxic gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Swarup, E-mail: swaruproy@klyuniv.ac.in [Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal (India); Das, Tapan Kumar [Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal (India); Maiti, Guru Prasad [Department of Molecular Biology and Biotechnology, University of Kalyani, Kalyani 741235, West Bengal (India); Department of Anesthesiology, Texas Tech University Health science Center, 3601 4th Street, Lubbock, TX 79430 (United States); Basu, Utpal [Department of Molecular Biology and Biotechnology, University of Kalyani, Kalyani 741235, West Bengal (India)

    2016-01-15

    Graphical abstract: The manuscript deals with the fungus mediated optimized biologically synthesized GNPs using Aspergillus foetidus and characterization of biosynthesized GNPs using various physico-chemical methods. The fairly stable synthesized nanoparticles have size in the range of 10–40 nm. Cytotoxicity study of biosynthesized GNPs on Human lung cancer cell line A549 showed no significant toxicity of GNPs. - Highlights: • A novel biosynthesis process of GNPs using Aspergillus foetidus. • Biosynthesized GNPs are in the range of 10–40 nm as observed from TEM. • This process of synthesis is an optimized biosynthesis process of GNPs. • Biosynthesized GNPs are noncytotoxic against A549 cell line. - Abstract: We study the extracellular biosynthesis of gold nanoparticles (GNPs) using the fungal species Aspergillus foetidus. The formation of GNPs were initially monitored by visual observation and then characterized with the help of various characterization techniques. X-ray diffraction (XRD) results revealed distinctive formation of face centered cubic crystalline GNPs. From field emission scanning electron microscopy (FESEM) the morphology of the nanoparticles were found to be roughly spherical and within the size range of 30–50 nm. The spherical and polydispersed GNPs in the range of 10–40 nm were observed by transmission electron microscopy (TEM) analysis. It was established that alkaline pH, 1 mM gold salt concentration and 75 °C temperature were the respective optimum parameter for biosynthesis of GNPs. Cell cytotoxicity of GNP was compared with that of normal gold salt solution on A549 cell. The A549 cell growth in presence of GNPs was found to be comparatively less toxic than the gold ion.

  7. Silver, gold, and alloyed silver-gold nanoparticles: characterization and comparative cell-biologic action

    Science.gov (United States)

    Mahl, Dirk; Diendorf, Jörg; Ristig, Simon; Greulich, Christina; Li, Zi-An; Farle, Michael; Köller, Manfred; Epple, Matthias

    2012-10-01

    Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly( N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 μg mL-1 induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

  8. Silver, gold, and alloyed silver-gold nanoparticles: characterization and comparative cell-biologic action

    Energy Technology Data Exchange (ETDEWEB)

    Mahl, Dirk; Diendorf, Joerg; Ristig, Simon [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Greulich, Christina [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Li Zian; Farle, Michael [University of Duisburg-Essen, Faculty of Physics, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Koeller, Manfred [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Epple, Matthias, E-mail: matthias.epple@uni-due.de [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany)

    2012-10-15

    Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly(N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 {mu}g mL{sup -1} induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

  9. Amoxicillin functionalized gold nanoparticles reverts MRSA resistance

    Energy Technology Data Exchange (ETDEWEB)

    Kalita, Sanjeeb; Kandimalla, Raghuram; Sharma, Kaustav Kalyan [Drug Discovery Lab, Life Science Division, Institute of Advanced Study in Science and Technology (IASST), Paschim Boragaon, Garchuk, Guwahati 781035, Assam (India); Kataki, Amal Chandra [Dr. B. Borooah Cancer Institute, Guwahati, Assam (India); Department of Applied Sciences, Gopinath Bordoloi Nagar, Jalukbari, Gauhati University, Guwahati 781014, Assam (India); Deka, Manab [Department of Applied Sciences, Gopinath Bordoloi Nagar, Jalukbari, Gauhati University, Guwahati 781014, Assam (India); Kotoky, Jibon, E-mail: jkotoky@gmail.com [Drug Discovery Lab, Life Science Division, Institute of Advanced Study in Science and Technology (IASST), Paschim Boragaon, Garchuk, Guwahati 781035, Assam (India)

    2016-04-01

    In this study, we have described the biosynthesis of biocompatible gold nanoparticles (GNPs) from aqueous extract of the aerial parts of a pteridophyte, “Adiantum philippense” by microwave irradiation and its surface functionalization with broad spectrum beta lactam antibiotic, amoxicillin (Amox). The functionalization of amoxicillin on GNPs (GNP-Amox) was carried out via electrostatic interaction of protonated amino group and thioether moiety mediated attractive forces. The synthesized GNPs and GNP-Amox were physicochemically characterized. UV–Vis spectroscopy, Zeta potential, XRD, FTIR and SERS (surface enhanced raman spectra) results confirmed the loading of Amox into GNPs. Loading of Amox to GNPs reduce amoxicillin cytotoxicity, whereas GNPs were found to be nontoxic to mouse fibroblast cell line (L929) as evident from MTT and acridine orange/ethidium bromide (AO/EtBr) live/dead cell assays. The GNP-Amox conjugates demonstrated enhanced broad-spectrum bactericidal activity against both Gram-positive and Gram-negative bacteria. Furthermore, in-vitro and in-vivo assays of GNP-Amox revealed potent anti-MRSA activity and improved the survival rate. This indicates the subversion of antibiotic resistance mechanism by overcoming the effect of high levels of β-lactamase produced by methicillin resistant Staphylococcus aureus (MRSA). Taken together, this study demonstrates the positive attributes from GNP-Amox conjugates as a promising antibacterial therapeutic agent against MRSA as well as other pathogens. - Highlights: • Aqueous extract of A. phillippens was used as a reducing and capping agent for synthesis of microwave irradiated gold nanoparticles. • GNPs were loaded with amoxicillin for restoration in antibacterial activity of amoxicillin against MRSA strains. • Gold nanoparticles and GNP-Amox were found biocompitable as tested on L929 cell line. • The nanoparticle antibiotic conjugates exhibited restoration of amoxicillin activity against MRSA in

  10. Phonon assisted thermophoretic motion of gold nanoparticles inside carbon nanotubes

    Science.gov (United States)

    Schoen, Philipp A. E.; Walther, Jens H.; Poulikakos, Dimos; Koumoutsakos, Petros

    2007-06-01

    The authors investigate the thermally driven mass transport of gold nanoparticles confined inside carbon nanotubes using molecular dynamics simulations. The observed thermophoretic motion of the gold nanoparticles correlates with the phonon dispersion exhibited by a standard carbon nanotube and, in particular, with the breathing mode of the tube. Additionally, the results show an increased static friction for gold nanoparticles confines inside a zig-zag carbon nanotube when increasing the size (length) of the nanoparticles. However, an unexpected, opposite trend is observed for the same nanoparticles inside armchair tubes.

  11. Phonon assisted thermophoretic motion of gold nanoparticles inside carbon nanotubes

    DEFF Research Database (Denmark)

    Schoen, Philipp A.E.; Walther, Jens Honore; Poulikakos, Dimos

    2007-01-01

    The authors investigate the thermally driven mass transport of gold nanoparticles confined inside carbon nanotubes using molecular dynamics simulations. The observed thermophoretic motion of the gold nanoparticles correlates with the phonon dispersion exhibited by a standard carbon nanotube and......, in particular, with the breathing mode of the tube. Additionally, the results show an increased static friction for gold nanoparticles confines inside a zig-zag carbon nanotube when increasing the size length of the nanoparticles. However, an unexpected, opposite trend is observed for the same nanoparticles...

  12. Biodistribution of gold nanoparticles following intratracheal instillation in mouse lung

    DEFF Research Database (Denmark)

    Sadauskas, Evaldas; Jacobsen, Nicklas R.; Danscher, Gorm

    2009-01-01

    repeatedly during 3 weeks, the load was substantial. Ultrastructurally, AMG silver enhanced gold nanoparticles were found in lysosome-/endosome-like organelles of the macrophages and analysis with AMG, ICP-MS and NAA of the liver revealed an almost total lack of translocation of nanoparticles. In mice given......Background The fate of gold nanoparticles, 2, 40 and 100 nm, administered intratracheally to adult female mice was examined. The nanoparticles were traced by autometallography (AMG) at both ultrastructural and light microscopic levels. Also, the gold content was quantified by inductively coupled...... plasma mass spectrometry (ICP-MS) and neutron activation analysis (NAA). The liver is the major site of deposition of circulating gold nanoparticles. Therefore the degree of translocation was determined by the hepatic deposition of gold. Mice were instilled with 5 intratracheal doses of gold...

  13. Synthesis of gold nanoparticles and silver nanoparticles via green technology

    Science.gov (United States)

    Ahmed, Zulfiqaar; Balu, S. S.

    2012-11-01

    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.

  14. Biological response of hydrogels embedding gold nanoparticles.

    Science.gov (United States)

    Marsich, Eleonora; Travan, Andrea; Donati, Ivan; Di Luca, Andrea; Benincasa, Monica; Crosera, Matteo; Paoletti, Sergio

    2011-04-01

    A nanocomposite hydrogel based on natural polysaccharides and gold nanoparticles (ACnAu) has been prepared and its biological effects were tested in vitro with both bacteria and eukaryotic cells. Antimicrobial tests showed that AC-nAu gels are effective in killing both gram+ (Staphylococcus aureus) and gram- (Pseudomonas aeruginosa) bacteria. LDH assays pointed at a toxic effect towards eukaryotic cell-lines (HepG2 and MG63), in contrast with the case of silver-based hydrogels; cytofluorimetry studies demonstrated an apoptosis-related mechanism induced by increase of ROS intracellular level which leads to cell death after 24 h of direct contact with AC-nAu gels. In vivo biocompatibility has been evaluated in a rat model, investigating the peri-implant soft tissue reaction after 1 month of implantation. The results show that silver-containing samples induced a fibrotic capsule of the same average thickness of the control sample (devoid of nanoparticles) (∼50 μm), while in the case of gold containing materials the fibrotic capsule was thicker (∼100 μm), confirming a higher biocompatibility for silver-based samples than for gold-based ones.

  15. Irradiation stability and cytotoxicity of gold nanoparticles for radiotherapy

    Directory of Open Access Journals (Sweden)

    Xiao-Dong Zhang

    2009-09-01

    Full Text Available Xiao-Dong Zhang1, Mei-Li Guo2, Hong-Ying Wu1, Yuan-Ming Sun1, Yan-Qiu Ding1, Xin Feng1, Liang-An Zhang11Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People’s Republic of China; 2Department of Physics, Tianjin Institute of Urban Construction, Tianjin, People’s Republic of ChinaAbstract: Gold nanoparticles are promising as a kind of novel radiosensitizer in radiotherapy. If gold nanoparticles are shown to have good irradiation stability and biocompatibility, they would play an important role in radiotherapy. In this work, we investigated irradiation effects of gold nanoparticles under 2–10 kR gamma irradiation and cytotoxicity of gold nanoparticles with human K562 cells by using Cell Titre-Glo™ luminescent cell viability assay. The results revealed that gamma irradiation had not induced any obvious instability and size variations in gold nanoparticles. We found that gold nanoparticles showed excellent radiation hardness with an absorbed dose conversation factor of 9.491 rad/R. Meanwhile, the surface plasmon resonance of gold nanoparticles was enhanced obviously after 2–10 kR gamma irradiation. Subsequently, cytotoxicity tests indicated that the extremely high concentration of gold nanoparticles could cause a sharp decrease in K562 cell viability, while the low concentration of gold nanoparticles had no obvious influence on the cell viability. Our results revealed that gold nanoparticles were stable under high-energy ray irradiation and showed concentration-dependent cytotoxicity.Keywords: gold nanoparticles, gamma ray effects, colloids, cytotoxicity

  16. The size distribution of 'gold standard' nanoparticles.

    Science.gov (United States)

    Bienert, Ralf; Emmerling, Franziska; Thünemann, Andreas F

    2009-11-01

    The spherical gold nanoparticle reference materials RM 8011, RM 8012, and RM 8013, with a nominal radius of 5, 15, and 30 nm, respectively, have been available since 2008 from NIST. These materials are recommended as standards for nanoparticle size measurements and for the study of the biological effects of nanoparticles, e.g., in pre-clinical biomedical research. We report on determination of the size distributions of these gold nanoparticles using different small-angle X-ray scattering (SAXS) instruments. Measurements with a classical Kratky type SAXS instrument are compared with a synchrotron SAXS technique. Samples were investigated in situ, positioned in capillaries and in levitated droplets. The number-weighted size distributions were determined applying model scattering functions based on (a) Gaussian, (b) log-normal, and (c) Schulz distributions. The mean radii are 4.36 +/- 0.04 nm (RM 8011), 12.20 +/- 0.03 nm (RM 8012), and 25.74 +/- 0.27 nm (RM 8013). Low polydispersities, defined as relative width of the distributions, were detected with values of 0.067 +/- 0.006 (RM 8011), 0.103 +/- 0.003, (RM 8012), and 0.10 +/- 0.01 (RM 8013). The results are in agreement with integral values determined from classical evaluation procedures, such as the radius of gyration (Guinier) and particle volume (Kratky). No indications of particle aggregation and particle interactions--repulsive or attractive--were found. We recommend SAXS as a standard method for a fast and precise determination of size distributions of nanoparticles.

  17. Tiopronin gold nanoparticle precursor forms aurophilic ring tetramer.

    Science.gov (United States)

    Simpson, Carrie A; Farrow, Christopher L; Tian, Peng; Billinge, Simon J L; Huffman, Brian J; Harkness, Kellen M; Cliffel, David E

    2010-12-06

    In the two step synthesis of thiolate-monolayer protected clusters (MPCs), the first step of the reaction is a mild reduction of gold(III) by thiols that generates gold(I) thiolate complexes as intermediates. Using tiopronin (Tio) as the thiol reductant, the characterization of the intermediate Au(4)Tio(4) complex was accomplished with various analytical and structural techniques. Nuclear magnetic resonance (NMR), elemental analysis, thermogravimetric analysis (TGA), and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) were all consistent with a cyclic gold(I)-thiol tetramer structure, and final structural analysis was gathered through the use of powder diffraction and pair distribution functions (PDF). Crystallographic data has proved challenging for almost all previous gold(I)-thiolate complexes. Herein, a novel characterization technique when combined with standard analytical assessment to elucidate structure without crystallographic data proved invaluable to the study of these complexes. This in conjunction with other analytical techniques, in particular mass spectrometry, can elucidate a structure when crystallographic data is unavailable. In addition, luminescent properties provided evidence of aurophilicity within the molecule. The concept of aurophilicity has been introduced to describe a select group of gold-thiolate structures, which possess unique characteristics, mainly red photoluminescence and a distinct Au-Au intramolecular distance indicating a weak metal-metal bond as also evidenced by the structural model of the tetramer. Significant features of both the tetrameric and the aurophilic properties of the intermediate gold(I) tiopronin complex are retained after borohydride reduction to form the MPC, including gold(I) tiopronin partial rings as capping motifs, or "staples", and weak red photoluminescence that extends into the Near Infrared region.

  18. Grafting single molecule magnets on gold nanoparticles.

    Science.gov (United States)

    Perfetti, Mauro; Pineider, Francesco; Poggini, Lorenzo; Otero, Edwige; Mannini, Matteo; Sorace, Lorenzo; Sangregorio, Claudio; Cornia, Andrea; Sessoli, Roberta

    2014-01-29

    The chemical synthesis and characterization of the first hybrid material composed by gold nanoparticles and single molecule magnets (SMMs) are described. Gold nanoparticles are functionalized via ligand exchange using a tetrairon(III) SMM containing two 1,2-dithiolane end groups. The grafting is evidenced by the shift of the plasmon resonance peak recorded with a UV-vis spectrometer, by the suppression of nuclear magnetic resonance signals, by X-ray photoemission spectroscopy peaks, and by transmission electron microscopy images. The latter evidence the formation of aggregates of nanoparticles as a consequence of the cross-linking ability of Fe4 through the two 1,2-dithiolane rings located on opposite sides of the metal core. The presence of intact Fe4 molecules is directly proven by synchrotron-based X-ray absorption spectroscopy and X-ray magnetic circular dichroism spectroscopy, while a detailed magnetic characterization, obtained using electron paramagnetic resonance and alternating-current susceptibility, confirms the persistence of SMM behavior in this new hybrid nanostructure. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Synthesis and Characterization of Gold Nanoparticles by Tryptophane

    Directory of Open Access Journals (Sweden)

    Azim Akbarzadeh

    2009-01-01

    Full Text Available Problem statement: Preparation and synthesis of gold nanoparticles with small size and suitable stability is very important and applicable particularly in medicine. In this study, we have prepared gold nanoparticles by chemical reduction method employing L-Tryptophane as a reducing agent for ionic gold. Approach: The gold nanoparticles are the most employed amongst the different metallic nanoparticles in the fields of nanomedicine and nanobiotechnology. Therefore, the employed method should provide suitable particle size, shape and particle distribution in order to obtain nanoparticles of high activity and efficiency indicating the importance of the technique. In this study, HAuCl4 .3H2O, L-Tryptophane and polyethyleneglycol (PEG were used to produce AuCl-4 ions. They were acted as pre-material, reducing and stabilizing agents respectively. Results: The size, distribution and formation of gold nanoparticles were confirmed by Transmission Electron Microscopy (TEM indicating the diameter of gold nanoparticles at the range of 10-25 nm and UV spectroscopy. The formed nanoparticles showed the highest absorption at 518 nm. Conclusion: The gold nanoparticles were stable in PEG1000. Since these nanoparticles have suitable size distribution they can be considered as a suitable candidate to be employed in nanomedicine and nanobiotechnology.

  20. Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles

    DEFF Research Database (Denmark)

    León, John Jairo Castillo; Bertel, Linda; Páez-Mozo, Edgar

    2013-01-01

    In this paper we present a rapid and simple onepot method to obtain gold nanoparticles functionalized with folic acid using a photochemistry method. The bioconjugate folic acid-gold nanoparticle was generated in one step using a photo-reduction method, mixing hydrogen tetrachloroaurate with folic...

  1. Undergraduate Laboratory Experiment Modules for Probing Gold Nanoparticle Interfacial Phenomena

    Science.gov (United States)

    Karunanayake, Akila G.; Gunatilake, Sameera R.; Ameer, Fathima S.; Gadogbe, Manuel; Smith, Laura; Mlsna, Deb; Zhang, Dongmao

    2015-01-01

    Three gold-nanoparticle (AuNP) undergraduate experiment modules that are focused on nanoparticles interfacial phenomena have been developed. Modules 1 and 2 explore the synthesis and characterization of AuNPs of different sizes but with the same total gold mass. These experiments enable students to determine how particle size affects the AuNP…

  2. Functionalized Gold Nanoparticles: Synthesis, Properties and Applications--A Review.

    Science.gov (United States)

    Alex, Saji; Tiwari, Ashutosh

    2015-03-01

    The past few decades have witnessed significant advances in the development of functionalized gold nanoparticles for applications in various fields such as chemistry, biology, pharmacy and physics. Although it has been more than 150 years since they were first synthesized, extensive research has recently been undertaken to improve or modify gold nanoparticles, thereby opening up opportunities to enhance and optimize their potential and breadth of their applicability. Recently developed methods have allowed a precise control of gold nanoparticle size and the modification of gold nanoparticles with suitable protecting and functionalizing agents, facilitate their applications in different areas such as chemical and biological sensing, imaging and biomedical applications. This review focuses on the recent developments in various methods for the size and shape controlled synthesis of gold nanoparticles, understanding of different properties of gold nanoparticles and their applications in various fields. Particular attention is given to the chemical and biological sensing applications of gold nanoparticles and on the advances in the controlled ordering of gold nanoparticles for creating nanostructures for diverse applications.

  3. Gold Nanoparticle Assemblies through Hydrogen-Bonded Supramolecular Mediators

    NARCIS (Netherlands)

    Kinge, Sachin S.; Crego-Calama, Mercedes; Reinhoudt, David N.

    2007-01-01

    The synthesis of spherical gold nanoparticle assemblies with multicomponent double rosette molecular boxes as mediators is presented. These nine-component hydrogen-bonded supramolecular structures held together by 36 hydrogen bonds induce gold nanoparticle assembly. The morphologies of the nanoparti

  4. Solidification of gold nanoparticles in carbon nanotubes.

    Science.gov (United States)

    Arcidiacono, S; Walther, J H; Poulikakos, D; Passerone, D; Koumoutsakos, P

    2005-03-18

    The structure and the solidification of gold nanoparticles in a carbon nanotube are investigated using molecular dynamics simulations. The simulations indicate that the predicted solidification temperature of the enclosed particle is lower than its bulk counterpart, but higher than that observed for clusters placed in vacuum. A comparison with a phenomenological model indicates that, in the considered range of tube radii (R(CNT)) of 0.5 < R(CNT) < 1.6 nm, the solidification temperature depends mainly on the length of the particle with a minor dependence on R(CNT).

  5. Application of gold nanoparticles in cancer therapy.

    Science.gov (United States)

    Zhao, Chuan-tong; Liu, Zhen-bao

    2014-06-01

    With their unique physicochemical properties including excellent stability and biocompatibility, large specific surface area, and easy surface modification, gold nanoparticles (AuNPs) can be used as delivery vectors for drugs, genes, proteins, etc. In addition, AuNPs have excellent photothermal effects and radiosensitization characteristics, and therefore can be widely applied in the photothermal therapy and radiotherapy of cancers. This article reviews the construction, cellular uptake, and drug release of AuNPs drug-delivery systems and their applications in the treatment of tumors.

  6. Interaction of gold nanoparticles with nanosecond laser pulses: Nanoparticle heating

    Energy Technology Data Exchange (ETDEWEB)

    Nedyalkov, N.N., E-mail: nnn_1900@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Imamova, S.E.; Atanasov, P.A. [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Toshkova, R.A.; Gardeva, E.G.; Yossifova, L.S.; Alexandrov, M.T. [Institute of Experimental Pathology and Parasitology, Bulgarian Academy of Sciences, G. Bonchev Street, bl. 25, Sofia 1113 (Bulgaria); Obara, M. [Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

    2011-04-01

    Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.

  7. Green Chemistry Techniques for Gold Nanoparticles Synthesis

    Science.gov (United States)

    Cannavino, Sarah A.; King, Christy A.; Ferrara, Davon W.

    Gold nanoparticles (AuNPs) are often utilized in many technological and research applications ranging from the detection of tumors, molecular and biological sensors, and as nanoantennas to probe physical processes. As these applications move from the research laboratory to industrial settings, there is a need to develop efficient and sustainable synthesis techniques. Recent research has shown that several food products and beverages containing polyphenols, a common antioxidant, can be used as reducing agents in the synthesis of AuNPs in solution. In this study, we explore a variety of products to determine which allow for the most reproducible solution of nanoparticles based on the size and shapes of particles present. We analyzed the AuNPs solutions using extinction spectroscopy and atomic force microscopy. We also develop a laboratory activity to introduce introductory chemistry and physics students to AuNP synthesis techniques and analysis.

  8. Silver and gold nanoparticles for sensor and antibacterial applications.

    Science.gov (United States)

    Bindhu, M R; Umadevi, M

    2014-07-15

    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.

  9. Synthesis and optical properties of colloidal gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Ngoc Long; Le Van Vu; Chu Dinh Kiem; Sai Cong Doanh; Cao Thi Nguyet; Pham Thi Hang; Nguyen Duy Thien; Luu Manh Quynh [Faculty of Physics, Hanoi University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam)], E-mail: longnn@vnu.edu.vn

    2009-09-01

    Colloidal gold nanoparticles (spheres) have been prepared from HAuCl{sub 4} containing aqueous solution by using X-ray irradiation and by chemical reduction method. Gold nanorods were synthesized according to the seed-mediated growth method. The colloidal gold nanoparticles were characterized by using transmission electron microscopy, X-ray diffraction, and UV-VIS absorption spectroscopy. It was found that the concentration of the precursors affects the size of the nanoparticles. In the chemical reduction approach the size of nanoparticles can be controlled by varying amount of trisodium citrate, but in the photochemical method the size of nanoparticles can been controlled by varying the ratio of HAuCl{sub 4} to TX-100 and X-ray irradiation duration. Gold nanorods have been synthesized according to the seed-mediated growth method with two steps. The effect of silver acetate and CTAB on formation of gold nanorods has been studied.

  10. Gold nanoparticles: From nanomedicine to nanosensing

    Directory of Open Access Journals (Sweden)

    Po C Chen

    2008-11-01

    Full Text Available Po C Chen, Sandra C Mwakwari, Adegboyega K OyelereSchool of Chemistry and Biochemistry, Parker H Petit Institute for Bioengineering and Bioscience, Atlanta, GA, USAAbstract: Because of their photo-optical distinctiveness and biocompatibility, gold nanoparticles (AuNPs have proven to be powerful tools in various nanomedicinal and nanomedical applications. In this review article, we discuss recent advances in the application of AuNPs in diagnostic imaging, biosensing and binary cancer therapeutic techniques. We also provide an eclectic collection of AuNPs delivery strategies, including assorted classes of delivery vehicles, which are showing great promise in specific targeting of AuNPs to diseased tissues. However, successful clinical implementations of the promised applications of AuNPs are still hampered by many barriers. In particular, more still needs to be done regarding our understanding of the pharmacokinetics and toxicological profiles of AuNPs and AuNPs-conjugates.Keywords: gold nanoparticles (AuNPs, targeted delivery, receptor-mediated endocytosis (RME, near infrared (NIR, surface plasmon resonance (SPR, surface-enhanced Raman scattering (SERS, bioimaging, biosensing, photothermal therapy

  11. Protein-mediated synthesis of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ravindra, Pratibha [Department of Life Sciences, University of Mumbai, Kalina, Santacruz (E) 400098, Mumbai (India)], E-mail: Pratibha.kamble@osumc.edu

    2009-07-15

    Our current approach is to synthesize gold nanoparticles utilizing Serrapeptase that serves as both a reducing and stabilizing agent. The investigations further reveal that certain amino acid groups like lysine are involved in reduction and stabilization of these particles. The particles are characterized with UV-vis spectroscopy, Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Proton Nuclear Magnetic Resonance (H NMR) Spectroscopy studies and Sodium dodecyl sulphate-polyacrylamide gel electrophoresis for Serrapeptidase and Au-Serrapeptidase isolation. Transmission electron microscopy studies show particles ranging from 20 nm to 200 nm that are spherical, hexagonal and polygonal in nature. UV-vis spectroscopy shows surface plasmon band at 536 nm that indicates formation of spherical particles whereas, results further add that gold particles are formed inside the nanosphere that is stabilized by interaction of amino acid groups like {gamma}-lysine of peptase. Fourier transform infrared spectroscopy studies reveal that few carboxyl groups are involved during the synthesis process followed by stretching of -CH bonds which has been seen in the case of lysine of Serrapeptase. Current studies therefore show that the method utilized for the synthesis of Au-nanoparticles is a biofriendly method and the nanogold formed can be a useful attribute for various applications.

  12. Microbial synthesis of Flower-shaped gold nanoparticles.

    Science.gov (United States)

    Singh, Priyanka; Kim, Yeon Ju; Wang, Chao; Mathiyalagan, Ramya; Yang, Deok Chun

    2016-09-01

    The shape of nanoparticles has been recognized as an important attribute that determines their applicability in various fields. The flower shape (F-shape) has been considered and is being focused on, because of its enhanced properties when compared to the properties of the spherical shape. The present study proposed the microbial synthesis of F-shaped gold nanoparticles within 48 h using the Bhargavaea indica DC1 strain. The F-shaped gold nanoparticles were synthesized extracellularly by the reduction of auric acid in the culture supernatant of B. indica DC1. The shape, size, purity, and crystalline nature of F-shaped gold nanoparticles were revealed by various instrumental techniques including UV-Vis, FE-TEM, EDX, elemental mapping, XRD, and DLS. The UV-Vis absorbance showed a maximum peak at 536 nm. FE-TEM revealed the F-shaped structure of nanoparticles. The EDX peak obtained at 2.3 keV indicated the purity. The peaks obtained on XRD analysis corresponded to the crystalline nature of the gold nanoparticles. In addition, the results of elemental mapping indicated the maximum distribution of gold elements in the nanoproduct obtained. Particle size analysis revealed that the average diameter of the F-shaped gold nanoparticles was 106 nm, with a polydispersity index (PDI) of 0.178. Thus, the methodology developed for the synthesis of F-shaped gold nanoparticles is completely green and economical.

  13. Resonant Modes of L-Shaped Gold Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    YANG Jing; ZHANG Jia-Sen; WU Xiao-Fei; GONG Qi-Huang

    2009-01-01

    We analyze the electric field modes excited in resonant L-shaped gold nanoparticles using a finite-difference time domain method.Compared to a single gold nanorod,both the odd and even modes of the L-shaped nanoparticles can be excited due to the symmetry breaking.The nanoparticles with equal and unequal arms have different dependence of field enhancement and mode on the incident polarization.

  14. Photoswitchable NIR-Emitting Gold Nanoparticles.

    Science.gov (United States)

    Bonacchi, Sara; Cantelli, Andrea; Battistelli, Giulia; Guidetti, Gloria; Calvaresi, Matteo; Manzi, Jeannette; Gabrielli, Luca; Ramadori, Federico; Gambarin, Alessandro; Mancin, Fabrizio; Montalti, Marco

    2016-09-05

    Photo-switching of the NIR emission of gold nanoparticles (GNP) upon photo-isomerization of azobenzene ligands, bound to the surface, is demonstrated. Photophysical results confirm the occurrence of an excitation energy transfer process from the ligands to the GNP that produces sensitized NIR emission. Because of this process, the excitation efficiency of the gold core, upon excitation of the ligands, is much higher for the trans form than for the cis one, and t→c photo-isomerization causes a relevant decrease of the GNP NIR emission. As a consequence, photo-isomerization can be monitored by ratiometric detection of the NIR emission upon dual excitation. The photo-isomerization process was followed in real-time through the simultaneous detection of absorbance and luminescence changes using a dedicated setup. Surprisingly, the photo-isomerization rate of the ligands, bound to the GNP surface, was the same as measured for the chromophores in solution. This outcome demonstrated that excitation energy transfer to gold assists photo-isomerization, rather than competing with it. These results pave the road to the development of new, NIR-emitting, stimuli-responsive nanomaterials for theranostics.

  15. Quantitative gold nanoparticle analysis methods: A review.

    Science.gov (United States)

    Yu, Lei; Andriola, Angelo

    2010-08-15

    Research and development in the area of gold nanoparticles' (AuNPs) preparation, characterization, and applications are burgeoning in recent years. Many of the techniques and protocols are very mature, but two major concerns are with the mass domestic production and the consumption of AuNP based products. First, how many AuNPs exist in a dispersion? Second, where are the AuNPs after digestion by the environment and how many are there? To answer these two questions, reliable and reproducible methods are needed to analyze the existence and the population of AuNP in samples. This review summarized the most recent chemical and particle quantitative analysis methods that have been used to characterize the concentration (in number of moles of gold per liter) or population (in number of particles per mL) of AuNPs. The methods summarized in this review include, mass spectroscopy, electroanalytical methods, spectroscopic methods, and particle counting methods. These methods may count the number of AuNP directly or analyze the total concentration of element gold in an AuNP dispersion.

  16. Inkjet-printed gold nanoparticle surfaces for the detection of low molecular weight biomolecules by laser desorption/ionization mass spectrometry.

    Science.gov (United States)

    Marsico, Alyssa L M; Creran, Brian; Duncan, Bradley; Elci, S Gokhan; Jiang, Ying; Onasch, Timothy B; Wormhoudt, Joda; Rotello, Vincent M; Vachet, Richard W

    2015-11-01

    Effective detection of low molecular weight compounds in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is often hindered by matrix interferences in the low m/z region of the mass spectrum. Here, we show that monolayer-protected gold nanoparticles (AuNPs) can serve as alternate matrices for the very sensitive detection of low molecular weight compounds such as amino acids. Amino acids can be detected at low fmol levels with minimal interferences by properly choosing the AuNP deposition method, density, size, and monolayer surface chemistry. By inkjet-printing AuNPs at various densities, we find that AuNP clusters are essential for obtaining the greatest sensitivity. Graphical Abstract ᅟ.

  17. Temperature driven transport of gold nanoparticles physisorbed inside carbon nanotubes

    DEFF Research Database (Denmark)

    Schoen, P.A.E.; Poulikakos, D.; Walther, Jens Honore

    2006-01-01

    We use molecular dynamics simulations to demonstrate the temperature driven mass transport of solid gold nanoparticles, physisorbed inside carbon nanotubes (CNTs). Our results indicate that the nanoparticle experiences a guided motion, in the direction opposite to the direction of the temperature...... affects the nanoparticle motion along the carbon lattice....

  18. Phytofabricated gold nanoparticles and their biomedical applications.

    Science.gov (United States)

    Ahmad, Bashir; Hafeez, Nabia; Bashir, Shumaila; Rauf, Abdur; Mujeeb-Ur-Rehman

    2017-02-26

    In a couple of decades, nanotechnology has become a trending technology owing to its integrated science collection that incorporates variety of fields such as chemistry, physics, medicine, catalytic processes, food processing industries, electronics and energy sectors. One of the emerging fields of nanotechnology that has gained momentous admiration is nano-biotechnology. Nano-biotechnology is an integrated combination of biology with nanotechnology that encompasses the tailoring, and synthesis of small particles that are less than 100nm in size and subsequent exploitation of these particles for their biological applications. Though the variety of physical techniques and chemical procedures are known for the nanoparticles synthesis, biological approach is considered to be the preferred one. Environmental hazards and concerns associated with the physical and chemical approaches of nanoparticles synthesis has added impetus and zenith to the biological approach involving the use of plants and microorganisms. The current review article is focused on the synthesis of plant-derived (phytochemical) gold nanoparticles alongside their scope in biomedical applications.

  19. Biophysical characterization of gold nanoparticles-loaded liposomes.

    Science.gov (United States)

    Mady, Mohsen Mahmoud; Fathy, Mohamed Mahmoud; Youssef, Tareq; Khalil, Wafaa Mohamed

    2012-10-01

    Gold nanoparticles were prepared and loaded into the bilayer of dipalmitoylphosphatidylcholine (DPPC) liposomes, named as gold-loaded liposomes. Biophysical characterization of gold-loaded liposomes was studied by transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy as well as turbidity and rheological measurements. FTIR measurements showed that gold nanoparticles made significant changes in the frequency of the CH(2) stretching bands, revealing that gold nanoparticles increased the number of gauche conformers and create a conformational change within the acyl chains of phospholipids. The transmission electron micrographs (TEM) revealed that gold nanoparticles were loaded in the liposomal bilayer. The zeta potential of DPPC liposomes had a more negative value after incorporating of Au NPs into liposomal membranes. Turbidity studies revealed that the loading of gold nanoparticles into DPPC liposomes results in shifting the temperature of the main phase transition to a lower value. The membrane fluidity of DPPC bilayer was increased by loading the gold nanoparticles as shown from rheological measurements. Knowledge gained in this study may open the door to pursuing liposomes as a viable strategy for Au NPs delivery in many diagnostic and therapeutic applications.

  20. GOLD NANOPARTICLES: A REVIVAL IN PRECIOUS METAL ADMINISTRATION TO PATIENTS

    Science.gov (United States)

    Thakor, AS; Jokerst, J; Zaveleta, C; Massoud, TF; Gambhir, SS

    2011-01-01

    Gold has been used as a therapeutic agent to treat a wide variety of rheumatic diseases including psoriatic arthritis, juvenile arthritis and discoid lupus erythematosus. Although the use of gold has been largely superseded by newer drugs, gold nanoparticles are being used effectively in laboratory based clinical diagnostic methods whilst concurrently showing great promise in vivo either as a diagnostic imaging agent or a therapeutic agent. For these reasons, gold nanoparticles are therefore well placed to enter mainstream clinical practice in the near future. Hence, the present review summarizes the chemistry, pharmacokinetics, bio-distribution, metabolism and toxicity of bulk gold in humans based on decades of clinical observation and experiments in which gold was used to treat patients with rheumatoid arthritis. The beneficial attributes of gold nanoparticles, such as their ease of synthesis, functionalization and shape control are also highlighted demonstrating why gold nanoparticles are an attractive target for further development and optimization. The importance of controlling the size and shape of gold nanoparticles to minimize any potential toxic side effects is also discussed. PMID:21846107

  1. Multifunctional gold nanoparticles for diagnosis and therapy of disease

    Science.gov (United States)

    Mieszawska, Aneta J.; Mulder, Willem J. M.; Fayad, Zahi A.

    2013-01-01

    Gold nanoparticles (AuNPs) have a number of physical properties that make them appealing for medical applications. For example, the attenuation of X-rays by gold nanoparticles has led to their use in computed tomography imaging and as adjuvants for radiotherapy. AuNPs have numerous other applications in imaging, therapy and diagnostic systems. The advanced state of synthetic chemistry of gold nanoparticles offers precise control over physicochemical and optical properties. Furthermore gold cores are inert and are considered to be biocompatible and non-toxic. The surface of gold nanoparticles can easily be modified for a specific application and ligands for targeting, drugs or biocompatible coatings can be introduced. AuNPs can be incorporated into larger structures such as polymeric nanoparticles or liposomes that deliver large payloads for enhanced diagnostic applications, efficiently encapsulate drugs for concurrent therapy or add additional imaging labels. This array of features has led to the afore-mentioned applications in biomedical fields, but more recently in approaches where multifunctional gold nanoparticles are used for multiple methods, such as concurrent diagnosis and therapy, so called theranostics. The following review covers basic principles and recent findings in gold nanoparticle applications for imaging, therapy and diagnostics, with a focus on reports of multifunctional AuNPs. PMID:23360440

  2. Self-Assembled Monolayer of Mixed Gold and Nickel Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Yanni Jie; Huiqing Fan; Wei You

    2012-01-01

    Forming a monolayer of mixed nickel and gold nanoparticles through self-assembly via simple solu-tion processing constitutes an important step toward inexpensive nanoparticle-based carbon nanofiber growth. In this work, mixed gold and nickel nanoparticles were anchored on the silicon wafer using self-assembled monolayers (SAMs) as a template. SAMs of 3-mercaptopropyl trimethoxysilane (MPTS-SAMs) were formed on silicon wafer, with the exposed thiol functionality providing ligand exchange sites to form the mixed mono-layer of nickel and gold nanoparticles via a two-step sequential soaking approach. The densities of the nickel and gold nanoparticles on the surface can be varied by adjusting the soaking sequence.

  3. Gold revolution--gold nanoparticles for modern medicine and surgery.

    Science.gov (United States)

    Rippel, Radoslaw A; Seifalian, Alexander M

    2011-05-01

    Nanotechnology is a new and exciting branch of science which offers enormous potential for development of medicine and surgery. Gold nanoparticles (GNP) is just one of a variety of nano products which will be available for physician of the future. GNP will give us more effective treatments and diagnosis. We are able to conjugate GNP with peptides, drugs, and other molecules to gain astonishing effects. High quality, non-invasive imaging will inevitably lead to astonishing accuracy diagnostic tools with effective use during surgery. The same principles may be used in the future for drug delivery and thermal treatment of cancer. Detailed DNA detection and regulation may become everyday use technology, in medicine with support from GNP based tools. Bacterial diagnostics and nerve repair are relatively poorly researched areas of application of GNP with possibly astonishing therapeutic effects. Non-invasive clearance of arteriosclerotic plagues with GNP shows a great prospect for further development of minimally invasive surgery. However, before all of those tools will become available for clinicians, in depth toxicology research as well as transitional research and design have to be done to ensure safe clinical practice with maximal benefit for patients.

  4. The use of gold nanoparticles to enhance radiotherapy in mice

    Energy Technology Data Exchange (ETDEWEB)

    Hainfeld, James F [Nanoprobes, Inc., 95 Horse Block Rd., Yaphank, NY 11980 (United States); Slatkin, Daniel N [Nanoprobes, Inc., 95 Horse Block Rd., Yaphank, NY 11980 (United States); Smilowitz, Henry M [Department of Pharmacology, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030 (United States)

    2004-09-21

    Mice bearing subcutaneous EMT-6 mammary carcinomas received a single intravenous injection of 1.9 nm diameter gold particles (up to 2.7 g Au/kg body weight), which elevated concentrations of gold to 7 mg Au/g in tumours. Tumour-to-normal-tissue gold concentration ratios remained {approx}8:1 during several minutes of 250 kVp x-ray therapy. One-year survival was 86% versus 20% with x-rays alone and 0% with gold alone. The increase in tumours safely ablated was dependent on the amount of gold injected. The gold nanoparticles were apparently non-toxic to mice and were largely cleared from the body through the kidneys. This novel use of small gold nanoparticles permitted achievement of the high metal content in tumours necessary for significant high-Z radioenhancement. (note)

  5. The use of gold nanoparticles to enhance radiotherapy in mice.

    Science.gov (United States)

    Hainfeld, James F; Slatkin, Daniel N; Smilowitz, Henry M

    2004-09-21

    Mice bearing subcutaneous EMT-6 mammary carcinomas received a single intravenous injection of 1.9 nm diameter gold particles (up to 2.7 g Au/kg body weight), which elevated concentrations of gold to 7 mg Au/g in tumours. Tumour-to-normal-tissue gold concentration ratios remained approximately 8:1 during several minutes of 250 kVp x-ray therapy. One-year survival was 86% versus 20% with x-rays alone and 0% with gold alone. The increase in tumours safely ablated was dependent on the amount of gold injected. The gold nanoparticles were apparently non-toxic to mice and were largely cleared from the body through the kidneys. This novel use of small gold nanoparticles permitted achievement of the high metal content in tumours necessary for significant high-Z radioenhancement.

  6. Gold mining for PDT: Great expectations from tiny nanoparticles.

    Science.gov (United States)

    Gamaleia, Nikolai F; Shton, Irina O

    2015-06-01

    Among many and various products, born by the modern nanotechnology, gold nanoparticles roused a special interest of biomedical researchers. Unique features of the nanoparticles allow to use them not only as effective transporters for therapeutic agents but also as basic components of nanocomposite preparations intended for targeted photodynamic and photothermal therapy of tumours. In the review, physical, chemical and biological properties of gold nanoparticles which can promote PDT efficiency of a designed nanocomposite, are briefly characterized, and promising trends in creation of gold-containing composite photosensitizers are analysed.

  7. Subdiffraction scattered light imaging of gold nanoparticles using structured illumination.

    Science.gov (United States)

    Chang, Bo-Jui; Lin, Shiuan Huei; Chou, Li-Jun; Chiang, Su-Yu

    2011-12-15

    A reflective light-scattering (RLS) microscope with structured illumination (SI) provides subdiffraction resolution and improves the image quality of gold nanoparticles in biological systems. The three-dimensional (3D)-structured pattern is rapidly and precisely controlled with a spatial light modulator and scrambled at the conjugate image plane to increase spatial incoherence. The reconstructed SI-RLS image of 100 nm gold nanoparticles reveals lateral and axial resolutions of approximately 117 and 428 nm. We present a high-resolution image of gold nanoparticles inside a HeLa cell, with improved contrast.

  8. Tetrahedron DNA dendrimers and their encapsulation of gold nanoparticles.

    Science.gov (United States)

    Zhou, Tao; Wang, Yijie; Dong, Yuanchen; Chen, Chun; Liu, Dongsheng; Yang, Zhongqiang

    2014-08-15

    DNA dendrimers have achieved increasing attention recently. Previously reported DNA dendrimers used Y-DNA as monomers. Tetrahedron DNA is a rigid tetrahedral cage made of DNA. Herein, we use tetrahedron DNA as monomers to prepare tetrahedron DNA dendrimers. The prepared tetrahedron DNA dendrimers have larger size compared with those made of Y-DNA. In addition, thanks to the central cavity of tetrahedron DNA monomers, some nanoscale structures (e.g., gold nanoparticles) can be encapsulated within tetrahedron DNA monomers. Tetrahedron DNA encapsulated with gold nanoparticles can be further assembled into dendrimers, guiding gold nanoparticles into clusters.

  9. Infrared light-absorbing gold/gold sulfide nanoparticles induce cell death in esophageal adenocarcinoma

    Science.gov (United States)

    Li, Yan; Gobin, Andre M; Dryden, Gerald W; Kang, Xinqin; Xiao, Deyi; Li, Su Ping; Zhang, Guandong; Martin, Robert CG

    2013-01-01

    Gold nanoparticles and near infrared-absorbing light are each innocuous to tissue but when combined can destroy malignant tissue while leaving healthy tissue unharmed. This study investigated the feasibility of photothermal ablation therapy for esophageal adenocarcinoma using chitosan-coated gold/gold sulfide (CS-GGS) nanoparticles. A rat esophagoduodenal anastomosis model was used for the in vivo ablation study, and three human esophageal cell lines were used to study the response of cancer cells and benign cells to near infrared light after treatment with CS-GGS. The results indicate that both cancerous tissue and cancer cells took up more gold nanoparticles and were completely ablated after exposure to near infrared light. The benign tissue and noncancerous cells showed less uptake of these nanoparticles, and remained viable after exposure to near infrared light. CS-GGS nanoparticles could provide an optimal endoluminal therapeutic option for near infrared light ablation of esophageal cancer. PMID:23818775

  10. Optical Properties of Linoleic Acid Protected Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ratan Das

    2011-01-01

    Full Text Available Linoleic acid-protected gold nanoparticles have been synthesized through the chemical reduction of tetrachloroaurate ions by ethanol in presence of sodium linoleate. The structure of these nanoparticles is investigated using transmission electron microscopy, which shows that the Au nanoparticles are spherical in shape with a narrow size distribution which ranges from 8 to 15 nm. Colloidal dispersion of gold nanoparticles in cyclohexane exhibits absorption bands in the ultraviolet-visible range due to surface plasmon resonance, with absorption maximum at 530 nm. Fluorescence spectra of gold nanoparticles also show an emission peak at 610 nm when illuminated at 450 nm. UV-Vis spectroscopy reveals that these nanoparticles remain stable for 10 days.

  11. Biogenic synthesis of gold and silver nanoparticles by seed plants.

    Science.gov (United States)

    Iyer, R Indira; Panda, Tapobrata

    2014-02-01

    Nanoparticles have an enormous range of biomedical and environmental applications and can be used for development of various nanodevices for diagnostics and drug delivery. Biogenic production of nanoparticles, that is of silver and gold, by seed plants, especially flowering plants, has evoked considerable interest in the last decade. Different organs of plants as well as callus cultures have been used for the production of these metal nanoparticles. It is possible to regulate the geometry of the nanoparticles by modifying the experimental parameters. In many cases the phytosynthesized gold and silver nanoparticles have been demonstrated to be potentially useful for treatment of various diseases. The production of gold and silver nanoparticles by diverse species of seed plants and their biological activity are discussed in this article.

  12. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by scanning electron microscopy

    NARCIS (Netherlands)

    Hartsuiker, L.; Es, van P.; Petersen, W.; Leeuwen, van T.G.; Terstappen, L.W.M.M.; Otto, C.

    2011-01-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample

  13. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by Scanning Electron Microscopy

    NARCIS (Netherlands)

    Hartsuiker, Liesbeth; van Es, Peter; Petersen, Wilhelmina; van Leeuwen, Ton; Terstappen, Leonardus Wendelinus Mathias Marie; Otto, Cornelis

    2011-01-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample

  14. Extracellular mycosynthesis of gold nanoparticles using Fusarium solani

    Science.gov (United States)

    Gopinath, K.; Arumugam, A.

    2014-08-01

    The development of eco-friendly methods for the synthesis of nanomaterial shape and size is an important area of research in the field of nanotechnology. The present investigation deals with the extracellular rapid biosynthesis of gold nanoparticles using Fusarium solani culture filtrate. The UV-vis spectra of the fungal culture filtrate medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. FTIR spectra provide an evidence for the presence of heterocyclic compound in the culture filtrate, which increases the stability of the synthesized gold nanoparticles. The X-ray analysis respects the Bragg's law and confirmed the crystalline nature of the gold nanoparticles. AFM analysis showed the results of particle sizes (41 nm). Transmission electron microscopy (TEM) showed that the gold nanoparticles are spherical in shape with the size range from 20 to 50 nm. The use of F. solani will offer several advantages since it is considered as a non-human pathogenic organism. The fungus F. solani has a fast growth rate, rapid capacity of metallic ions reduction, NPs stabilization and facile and economical biomass handling. Extracellular biosynthesis of gold nanoparticles could be highly advantageous from the point of view of synthesis in large quantities, time consumption, eco-friendly, non-toxic and easy downstream processing.

  15. Preparation and bactericide activity of gallic acid stabilized gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Alvarez, S. A. [UASLP, Doctorado Institucional en Ingenieria y Ciencia de Materiales (Mexico); Martinez-Castanon, G. A., E-mail: mtzcastanon@fciencias.uaslp.m [UASLP, Maestria en Ciencias Odontologicas, Facultad de Estomatologia (Mexico); Nino-Martinez, N. [UASLP, Facultad de Ciencias (Mexico); Reyes-Macias, J. F.; Patino-Marin, N.; Loyola-Rodriguez, J. P. [UASLP, Maestria en Ciencias Odontologicas, Facultad de Estomatologia (Mexico); Ruiz, Facundo [UASLP, Facultad de Ciencias (Mexico)

    2010-10-15

    In this work, gold nanoparticles with three different sizes (13.7, 39.4, and 76.7 nm) were prepared using a simple aqueous method with gallic acid as the reducing and stabilizing agent, the different sizes were obtained varying some experimental parameters as the pH of the reaction and the amount of the gallic acid. The prepared nanoparticles were characterized using X-ray diffraction, transmission electron microscopy, dynamic light scattering, and UV-Vis spectroscopy. Samples were identified as elemental gold and present spherical morphology, a narrow size distribution and good stabilization according to TEM and DLS results. The antibacterial activity of this gallic acid stabilized gold nanoparticles against S. mutans (the etiologic agent of dental caries) was assessed using a microdilution method obtaining a minimum inhibitory concentration of 12.31, 12.31, and 49.25 {mu}g/mL for 13.7, 39.4, and 76.7 nm gold nanoparticles, respectively. The antibacterial assay showed that gold nanoparticles prepared in this work present a bactericide activity by a synergistic action with gallic acid. The MIC found for this nanoparticles are much lower than those reported for mixtures of gold nanoparticles and antibiotics.

  16. Preparation and bactericide activity of gallic acid stabilized gold nanoparticles

    Science.gov (United States)

    Moreno-Álvarez, S. A.; Martínez-Castañón, G. A.; Niño-Martínez, N.; Reyes-Macías, J. F.; Patiño-Marín, N.; Loyola-Rodríguez, J. P.; Ruiz, Facundo

    2010-10-01

    In this work, gold nanoparticles with three different sizes (13.7, 39.4, and 76.7 nm) were prepared using a simple aqueous method with gallic acid as the reducing and stabilizing agent, the different sizes were obtained varying some experimental parameters as the pH of the reaction and the amount of the gallic acid. The prepared nanoparticles were characterized using X-ray diffraction, transmission electron microscopy, dynamic light scattering, and UV-Vis spectroscopy. Samples were identified as elemental gold and present spherical morphology, a narrow size distribution and good stabilization according to TEM and DLS results. The antibacterial activity of this gallic acid stabilized gold nanoparticles against S. mutans (the etiologic agent of dental caries) was assessed using a microdilution method obtaining a minimum inhibitory concentration of 12.31, 12.31, and 49.25 μg/mL for 13.7, 39.4, and 76.7 nm gold nanoparticles, respectively. The antibacterial assay showed that gold nanoparticles prepared in this work present a bactericide activity by a synergistic action with gallic acid. The MIC found for this nanoparticles are much lower than those reported for mixtures of gold nanoparticles and antibiotics.

  17. Modelling encapsulation of gold and silver nanoparticles inside lipid nanotubes

    Science.gov (United States)

    Baowan, Duangkamon; Thamwattana, Ngamta

    2014-02-01

    Lipid nanotubes are of particular interest for use as a template to create various one-dimensional nanostructures and as a carrier for drug and gene delivery. Understanding the encapsulation process is therefore crucial for such development. This paper models the interactions between lipid nanotubes and spheres of gold and silver nanoparticles and determines the critical dimension of lipid nanotubes that maximises the interaction with the nanoparticles. Our results confirm the acceptance of gold and silver nanoparticles inside lipid nanotubes. Further, we find that the lipid nanotube of radius approximately 10.23 nm is most favourable to encapsulate both types of nanoparticles.

  18. Exploitation of marine bacteria for production of gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Sharma Nishat

    2012-06-01

    Full Text Available Abstract Background Gold nanoparticles (AuNPs have found wide range of applications in electronics, biomedical engineering, and chemistry owing to their exceptional opto-electrical properties. Biological synthesis of gold nanoparticles by using plant extracts and microbes have received profound interest in recent times owing to their potential to produce nanoparticles with varied shape, size and morphology. Marine microorganisms are unique to tolerate high salt concentration and can evade toxicity of different metal ions. However, these marine microbes are not sufficiently explored for their capability of metal nanoparticle synthesis. Although, marine water is one of the richest sources of gold in the nature, however, there is no significant publication regarding utilization of marine micro-organisms to produce gold nanoparticles. Therefore, there might be a possibility of exploring marine bacteria as nanofactories for AuNP biosynthesis. Results In the present study, marine bacteria are exploited towards their capability of gold nanoparticles (AuNPs production. Stable, monodisperse AuNP formation with around 10 nm dimension occur upon exposure of HAuCl4 solution to whole cells of a novel strain of Marinobacter pelagius, as characterized by polyphasic taxonomy. Nanoparticles synthesized are characterized by Transmission electron microscopy, Dynamic light scattering and UV-visible spectroscopy. Conclusion The potential of marine organisms in biosynthesis of AuNPs are still relatively unexplored. Although, there are few reports of gold nanoparticles production using marine sponges and sea weeds however, there is no report on the production of gold nanoparticles using marine bacteria. The present work highlighted the possibility of using the marine bacterial strain of Marinobacter pelagius to achieve a fast rate of nanoparticles synthesis which may be of high interest for future process development of AuNPs. This is the first report of Au

  19. Bayesian object classification of gold nanoparticles

    KAUST Repository

    Konomi, Bledar A.

    2013-06-01

    The properties of materials synthesized with nanoparticles (NPs) are highly correlated to the sizes and shapes of the nanoparticles. The transmission electron microscopy (TEM) imaging technique can be used to measure the morphological characteristics of NPs, which can be simple circles or more complex irregular polygons with varying degrees of scales and sizes. A major difficulty in analyzing the TEM images is the overlapping of objects, having different morphological properties with no specific information about the number of objects present. Furthermore, the objects lying along the boundary render automated image analysis much more difficult. To overcome these challenges, we propose a Bayesian method based on the marked-point process representation of the objects. We derive models, both for the marks which parameterize the morphological aspects and the points which determine the location of the objects. The proposed model is an automatic image segmentation and classification procedure, which simultaneously detects the boundaries and classifies the NPs into one of the predetermined shape families. We execute the inference by sampling the posterior distribution using Markov chainMonte Carlo (MCMC) since the posterior is doubly intractable. We apply our novel method to several TEM imaging samples of gold NPs, producing the needed statistical characterization of their morphology. © Institute of Mathematical Statistics, 2013.

  20. Synthesis, capping and binding of colloidal gold nanoparticles to proteins

    Science.gov (United States)

    Nghiem, Thi Ha Lien; Huyen La, Thi; Hoa Vu, Xuan; Chu, Viet Ha; Hai Nguyen, Thanh; Huan Le, Quang; Fort, Emmanuel; Hoa Do, Quang; Nhung Tran, Hong

    2010-06-01

    Bovine serum albumin (BSA) was used as a stabilizing agent and biofunctionalized layer for water-dispersed gold nanoparticles (NPs) synthesized from metal precursor HAuCl4. The BSA binding to gold NPs was characterized qualitatively and quantitatively by transmission electron microscopy, UV-VIS and FTIR spectrophotometers. HER2 (human epidermal growth factor receptor 2) specific phage antibodies were attached to BSA stabilized gold NPs to form a gold-antibody complex. An ELISA (enzyme-linked immunosorbent assay) test was done to confirm the bioactivity of antibodies attached to gold NPs.

  1. Quinone-Enriched Gold Nanoparticles in Bioelectrochemistry and Charge Storage

    DEFF Research Database (Denmark)

    Wagner, Michal; Qvortrup, Katrine; Tanner, David Ackland

    We are aiming at the development of a general electrochemical platform suitable for multifarious investigations of biogenic materials. The new platform can be attained by grafting organic/metal hybrids with quinone functionality. In-house made and customized anthraquinone derivatives (with linking...... groups ranging from thiophenes to thiols) were chosen as model compounds for linking together bulk quantities of gold nanoparticles and providing desired functionality. Anthraquinone thiophene and thiol derivatives were synthetized via Sonogashira coupling-type reactions. The synthetic pathways...... for merging gold nanoparticles with resultant anthraquinones include one-pot microwave assisted synthesis or after-mixing of separately prepared gold nanoparticles with selected compounds. The quinone-enriched gold nanoparticles can be transferred onto different electrode surfaces, thus enabling facile...

  2. Cells adhesion and growth on gold nanoparticle grafted glass

    Energy Technology Data Exchange (ETDEWEB)

    Novotna, Zdenka, E-mail: zdenka1.novotna@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague (Czech Republic); Reznickova, Alena; Kvitek, Ondrej; Kasalkova, Nikola Slepickova [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague (Czech Republic); Kolska, Zdenka [Faculty of Science, J. E. Purkyně University, Ústí nad Labem (Czech Republic); Svorcik, Vaclav [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague (Czech Republic)

    2014-07-01

    The surface of glass substrate was plasma treated, coated by gold nano-structures and subsequently grafted with nanoparticles. The samples were plasma treated, sputtered with Au nanostructures which was followed by grafting with biphenyl-4,4'-dithiol (BPD) and then gold nanoparticles. The wettability, optical and chemical properties and surface morphology were studied. The adhesion and proliferation of vascular smooth muscle cells (VSMCs) on the samples were investigated in-vitro as well. Grafting of gold nanoparticles with the dithiol increases the UV–vis absorbance, the surface becomes more hydrophobic, rougher and more rugged compared to pristine, sputtered and only dithiol treated surface. Gold nano-particles bound over dithiol and Au nanostructures cause better cell proliferation than purely BPD treated or pristine glass.

  3. Cytotoxicity of gold nanoparticles prepared by ultrasonic spray pyrolysis.

    Science.gov (United States)

    Rudolf, R; Friedrich, B; Stopić, S; Anžel, I; Tomić, S; Čolić, M

    2012-01-01

    The aim of this work was to study the cytotoxicity of different fractions of gold nanoparticles prepared by ultrasonic spray pyrolysis from gold scrap. The target cells were rat thymocytes, as a type of nonproliferating cells, and L929 mouse fibroblasts, as a type of continuous proliferating cells. Fractions 1 and 2, composed of pure gold nanoparticles, as determined by scanning electron microscopy with a combination of energy dispersive X-ray analysis, were nontoxic for thymocytes, but reduced moderately the proliferative activity of L929 cells. The inhibitory effect of fraction 2, containing particles smaller in size than fraction 1, was stronger. Fraction 3, composed of Au and up to 3% Cu was noncytotoxic for thymocytes, but was cytotoxic for L929 cells. Fraction 4, composed of Au and Ag nanoparticles, and fraction 5, composed of Au together with Cu, Ni, Zn, Fe, and In were cytotoxic for both thymocytes and L929 cells. These results suggest that USP enables the synthesis of pure gold nanoparticles with controlled size, even from gold scrap. However, microstructural analyses and biocompatibility testing are necessary for their proper selection from more cytotoxic gold nanoparticles, contaminated with other elements of gold alloys.

  4. Kinetics of gold nanoparticles in the human placenta.

    Science.gov (United States)

    Myllynen, Päivi K; Loughran, Michael J; Howard, C Vyvyan; Sormunen, Raija; Walsh, Adrian A; Vähäkangas, Kirsi H

    2008-10-01

    We studied the transfer of PEGylated gold nanoparticles through perfused human placenta. In 'once-through' perfusions using 15 and 30nm nanoparticles both maternal and fetal outflows were collected. Recirculating perfusions using 10 or 15nm nanoparticles lasted 6h. The gold concentration in samples was analysed on ICP-MS. The reference compound antipyrine crossed the placenta rapidly, as expected. In open perfusions nanoparticles were detected in maternal but not in fetal outflow, suggesting the lack of placental transfer. During 6h re-circulating perfusions, no particles were detected in fetal circulation. Using transmission electron microscopy (TEM) and silver enhancement, nanoparticles could be visualized in the placental tissue mainly in the trophoblastic cell layer. In in vitro experiments, nanoparticles were taken up by BeWo choriocarcinoma cells and retained inside the cells for an extended period of 48h. In conclusion, PEGylated gold nanoparticles of the size 10-30nm did not cross the perfused human placenta in detectable amounts into the fetal circulation within 6h. Whether PEGylated gold nanoparticles eventually are able to cross placenta and whether nanoparticles affect placental functions needs to be further studied.

  5. Toward efficient modification of large gold nanoparticles with DNA

    NARCIS (Netherlands)

    Gill, Ron; Göeken, Kristian; Subramaniam, Vinod

    2014-01-01

    DNA-coated gold nanoparticles are one of the most researched nano-bio hybrid systems. Traditionally their synthesis has been a long and tedious process, involving slow salt addition and long incubation steps. This stems from the fact that both DNA and gold particles are negatively charged, therefore

  6. Water-Soluble Gold Nanoparticles Protected by Fluorinated Amphiphilic Thiolates

    NARCIS (Netherlands)

    Gentilini, Cristina; Evangelista, Fabrizio; Rudolf, Petra; Franchi, Paola; Lucarini, Marco; Pasquato, Lucia

    2008-01-01

    The preparation and the properties of gold nanoparticles (Au NPs) protected by perfluorinated amphiphiles are described. The thiols were devised to form a perfluorinated region close to the gold surface and to have a hydrophilic portion in contact with the bulk solvent to impart solubility in water.

  7. Selective metallization by seeded growth on patterned gold nanoparticle arrays

    NARCIS (Netherlands)

    Raza, M.A.; Zandvliet, H.J.W.; Poelsema, B.; Kooij, E.S.

    2013-01-01

    We describe the selective metallization by electroless gold deposition on pre-patterned arrays of seed particles. In the first step, highly selective deposition of seeds (gold nanoparticles) on silicon oxide surfaces is achieved using pure water. In the second step, employing an electroless seeded g

  8. Toward efficient modification of large gold nanoparticles with DNA

    NARCIS (Netherlands)

    Gill, R.; Goeken, K.L.; Subramaniam, V.

    2014-01-01

    DNA-coated gold nanoparticles are one of the most researched nano-bio hybrid systems. Traditionally their synthesis has been a long and tedious process, involving slow salt addition and long incubation steps. This stems from the fact that both DNA and gold particles are negatively charged, therefore

  9. Melamine nanosensing with chondroitin sulfate-reduced gold nanoparticles.

    Science.gov (United States)

    Noh, Hwa Jung; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie

    2013-12-01

    Gold nanoparticles were green-synthesized using a glycosaminoglycan, chondroitin sulfate, as the reducing agent by mixing Au3+ and chondroitin sulfate under heating. Chondroitin sulfate-reduced gold nanoparticles were characterized by UV-Vis spectrophotometry, high resolution transmission electron microscopy and atomic force microscopy. The yield of Au3+ to Au0 was measured as 80.1% by inductively coupled plasma-atomic emission spectroscopy. A mostly spherical shape, with an average diameter of 44.68 +/- 11.25 nm, was observed from the atomic force microscopy images. Using chondroitin sulfate-reduced gold nanoparticles, we developed a melamine nanosensor that provides a simplified method to detect melamine in infant formula. With an increase in the melamine concentration in the gold nanoparticle solution, the characteristic surface plasmon resonance band of gold nanoparticles at 530 nm decreased, whereas a new peak appeared at 620 nm. There was a linear relationship between the absorbance ratio (A620/A530) and the melamine concentration in the range of 0.1-10 microM. The practical use of the proposed method was verified by quantifying melamine spiked in real infant formula at concentrations as low as 12.6 ppb. The nanosensing of melamine using chondroitin sulfate-reduced gold nanoparticles can be a promising technique for quick on-site melamine screening of milk products.

  10. Grafting of gold nanoparticles on polyethyleneterephthalate using dithiol interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Reznickova, A., E-mail: alena.reznickova@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague 6 (Czech Republic); Kolska, Z. [Faculty of Science, J.E. Purkyně University, Usti nad Labem (Czech Republic); Zaruba, K. [Department of Analytical Chemistry, Institute of Chemical Technology Prague, Prague (Czech Republic); Svorcik, V. [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague 6 (Czech Republic)

    2014-06-01

    Two different procedures of grafting of polyethyleneterephthalate (PET), modified by plasma treatment, with gold nanoparticles (nanospheres) are studied. In the first procedure the PET foil was grafted with biphenyl-4,4′-dithiol and subsequently with gold nanoparticles. In the second one the PET foil was grafted with gold nanoparticles previously coated by the same dithiol. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and electrokinetic analysis were used for characterization of the polymer surface at different modification steps. Gold nanoparticles were characterized by ultraviolet–visible spectroscopy. 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 it mediates subsequent grafting of the gold nanoparticles. - Highlights: • Two different techniques were used for coating of PET with gold nanoparticles. • Grafted GNPs were characterized by XPS, FTIR, UV–vis, zeta potential, AFM. • More effective coating is achieved by deposition of GNPs earlier grafted with thiol. • The studied structures may have potential application in electronics or biomedicine.

  11. Size control synthesis of starch capped-gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tajammul Hussain, S., E-mail: dr_tajammul@yahoo.c [Quaid-i-Azam University, Centre for Nano Science and Catalysis, National Centre for Physics (Pakistan); Iqbal, M.; Mazhar, M. [Quaid-i-Azam University, Department of Chemistry (Pakistan)

    2009-08-15

    Metallic gold nanoparticles have been synthesized by the reduction of chloroaurate anions [AuCl{sub 4}]{sup -} solution with hydrazine in the aqueous starch and ethylene glycol solution at room temperature and at atmospheric pressure. The characterization of synthesized gold nanoparticles by UV-vis spectroscopy, high resolution transmission electron microscopy (HRTEM), electron diffraction analysis, X-ray diffraction (XRD), and X-rays photoelectron spectroscopy (XPS) indicate that average size of pure gold nanoparticles is 3.5 nm, they are spherical in shape and are pure metallic gold. The concentration effects of [AuCl{sub 4}]{sup -} anions, starch, ethylene glycol, and hydrazine, on particle size, were investigated, and the stabilization mechanism of Au nanoparticles by starch polymer molecules was also studied by FT-IR and thermogravimetric analysis (TGA). FT-IR and TGA analysis shows that hydroxyl groups of starch are responsible of capping and stabilizing gold nanoparticles. The UV-vis spectrum of these samples shows that there is blue shift in surface plasmon resonance peak with decrease in particle size due to the quantum confinement effect, a supporting evidence of formation of gold nanoparticles and this shift remains stable even after 3 months.

  12. Direct evidence for ferromagnetic spin polarization in gold nanoparticles

    OpenAIRE

    Yamamoto, Y; Miura, T; Teranishi, T.; Miyake, M.; Hori, H.; Suzuki, M.; Kawamura, N.; Miyagawa, H; T. Nakamura; Kobayashi, K

    2004-01-01

    We report the first direct observation of ferromagnetic spin polarization of Au nanoparticles with a mean diameter of 1.9 nm using X-ray magnetic circular dichroism (XMCD). Owing to the element selectivity of XMCD, only the gold magnetization is explored. Magnetization of gold atoms estimated by XMCD shows a good agreement with the results obtained by conventional magnetometry. This result is evidence of intrinsic spin polarization in nano-sized gold.

  13. Direct Observation of Ferromagnetic Spin Polarization in Gold Nanoparticles

    OpenAIRE

    Yamamoto, Y; Miura, T; Suzuki, M.; Kawamura, N.; Miyagawa, H; T. Nakamura; Kobayashi, K; Teranishi, T.; Hori, H.

    2004-01-01

    We report the first direct observation of ferromagnetic spin polarization of Au nanoparticles with a mean diameter of 1.9 nm using x-ray magnetic circular dichroism (XMCD). Owing to the element selectivity of XMCD, only the gold magnetization is explored. Magnetization of gold atoms as estimated by XMCD shows a good agreement with results obtained by conventional magnetometry. This evidences intrinsic spin polarization in nanosized gold.

  14. Controlling the Shape and Crystallinity of Gold and Silver Nanoparticles

    Science.gov (United States)

    Personick, Michelle Louise

    The strong dependence of the optical, electronic, and catalytic properties of noble metal nanoparticles on their shape has necessitated the high-yield synthesis of gold and silver nanostructures with precisely defined morphologies. This directed synthesis requires a detailed mechanistic understanding of the chemical and physical factors which control nanoparticle shape; however, these mechanistic explanations are still incomplete. To this end, the work of this dissertation seeks to enhance the understanding of nanoparticle growth on a mechanistic level, while also developing synthetic methods for producing novel nanoparticle shapes. Chapter 1 describes the state of the art in shape-controlled noble metal nanoparticle synthesis prior to the work conducted in this dissertation. In Chapter 2, a method is reported for synthesizing {110}-faceted bipyramids and rhombic dodecahedra, in which the combination of a chloride-containing surfactant and a low concentration of silver ions leads to the stabilization of the {110} facets. Chapter 3 explores in mechanistic detail the use of silver underpotential deposition to control particle growth in the synthesis of four gold nanoparticle shapes: octahedra, rhombic dodecahedra, truncated ditetragonal prisms, and concave cubes. This mechanistic understanding is expanded in Chapter 4, where the independent and synergistic roles of silver ions and halide ions in the seed-mediated synthesis of gold nanoparticles are systematically probed, culminating in a set of design considerations for controlling the shape of gold nanoparticles. Chapter 5 investigates the role of excitation wavelength in controlling the rate of silver ion reduction in the plasmon-mediated synthesis of silver nanoparticles and describes the synthesis of silver cubes with an unusual twinning structure. Finally, Chapter 6 combines the mechanistic insights gained in Chapters 2-5 to address a standing challenge in shape-controlled gold nanoparticle synthesis: the direct

  15. Spectroscopic evidence for the adsorption of propene on gold nanoparticles Spectroscopic evidence for the adsorption of propene on gold nanoparticles

    NARCIS (Netherlands)

    Nijhuis, T.A.; Sacaliuc, E.; Beale, A.M.; van der Eerden, A.M.J.; Schouten, J.C.; Weckhuysen, B.M.

    2008-01-01

    The adsorption of propene on supported gold nanoparticles has been experimentally identified as a reaction step in the hydro-epoxidation of propene. This new finding was made possible by applying a detailed analysis of in situ measured XANES spectra. For this purpose, gold-on-silica catalysts were i

  16. Gold Nanoparticles with Stably Embedded Cu-64 and Their Use in Nanoparticle Research

    DEFF Research Database (Denmark)

    Jensen, A.I.; Frellsen, Anders Floor; Hansen, A. E.

    2016-01-01

    64Cu is a popular radionuclide for PET imaging and when 64Cu2+ is mixed with gold nanoparticles (AuNPs) it adheres to the gold surface. Taking advantage of this, we developed methods to trap the 64Cu within the AuNPs by embedding under additional layers of gold. This resulted in radiolabeling eff...

  17. Using femtosecond lasers to modify sizes of gold nanoparticles

    Science.gov (United States)

    da Silva Cordeiro, Thiago; Almeida de Matos, Ricardo; Silva, Flávia Rodrigues de Oliveira; Vieira, Nilson D.; Courrol, Lilia C.; Samad, Ricardo E.

    2016-04-01

    Metallic nanoparticles are important on several scientific, medical and industrial areas. The control of nanoparticles characteristics has fundamental importance to increase the efficiency on the processes and applications in which they are employed. The metallic nanoparticles present specific surface plasmon resonances (SPR). These resonances are related with the collective oscillations of the electrons presents on the metallic nanoparticle. The SPR is determined by the potential defined by the nanoparticle size and geometry. There are several methods of producing gold nanoparticles, including the use of toxic chemical polymers. We already reported the use of natural polymers, as for example, the agar-agar, to produce metallic nanoparticles under xenon lamp irradiation. This technique is characterized as a "green" synthesis because the natural polymers are inoffensive to the environment. We report a technique to produce metallic nanoparticles and change its geometrical and dimensional characteristics using a femtosecond laser. The 1 ml initial solution was irradiate using a laser beam with 380 mW, 1 kHz and 40 nm of bandwidth centered at 800 nm. The setup uses an Acousto-optic modulator, Dazzler, to change the pulses spectral profiles by introduction of several orders of phase, resulting in different temporal energy distributions. The use of Dazzler has the objective of change the gold nanoparticles average size by the changing of temporal energy distributions of the laser pulses incident in the sample. After the laser irradiation, the gold nanoparticles average diameter were less than 15 nm.

  18. Reactivity of Electron-Deficient Alkynes on Gold Nanoparticles

    OpenAIRE

    Leyva Perez, Antonio; Oliver Meseguer, Judit; Cabrero Antonino, Jose Ramón; Rubio Marqués, Paula; Serna, Pedro; Al-Resayes, Saud I.; Corma Canós, Avelino

    2013-01-01

    Propiolates cyclotrimerize in the presence of catalytic amounts of gold nanoparticles to give aryl benzoates in high yields and with turnover frequencies of thousands per hour. Types of alkynes other than propiolates do not react, and, if molecular oxygen is present and dissociated by the gold nanoparticles, electron-rich arenes engage with the propiolate to form a new C–C bond. The activation of propiolates and electron-rich arenes to form C–C bonds, beyond gold-catalyzed Michael additions, ...

  19. Optical manipulation and study of single gold nanoparticles in solution

    NARCIS (Netherlands)

    Ruijgrok, Paul Victor

    2012-01-01

    We combine optical trapping and far-field optical detection techniques in a novel approach to study single metal nanoparticles in solution. We demonstrate the first measurements of the acoustic vibrations of single gold nanoparticles optically trapped in water, and find evidence for intrinsic dampi

  20. Uptake and depuration of gold nanoparticles in Daphnia magna

    DEFF Research Database (Denmark)

    Skjolding, Lars Michael; Kern, Kristina; Hjorth, Rune

    2014-01-01

    This study presents a series of short-term studies (total duration 48 h) of uptake and depuration of engineered nanoparticles (ENP) in neonate Daphnia magna. Gold nanoparticles (Au NP) were used to study the influence of size, stabilizing agent and feeding on uptake and depuration kinetics...

  1. One-phase synthesis of gold nanoparticles with varied solubility.

    Science.gov (United States)

    Dubavik, Aliaksei; Lesnyak, Vladimir; Gaponik, Nikolai; Eychmüller, Alexander

    2011-08-16

    We developed a straightforward synthesis of gold nanoparticles with diameters in the range 2.1-7.0 nm which display solubility in both aqueous and nonpolar (toluene, chloroform) media. This versatile solubility of the nanoparticles is achieved by the use of a thiolated PEG capping agent. Their plasmon resonance band is virtually unaltered in different media.

  2. Uptake and depuration of gold nanoparticles in Daphnia magna

    DEFF Research Database (Denmark)

    Skjolding, Lars Michael; Kern, Kristina; Hjorth, Rune

    2014-01-01

    This study presents a series of short-term studies (total duration 48 h) of uptake and depuration of engineered nanoparticles (ENP) in neonate Daphnia magna. Gold nanoparticles (Au NP) were used to study the influence of size, stabilizing agent and feeding on uptake and depuration kinetics...

  3. Shape-controlled Synthesis of Gold Nanoparticles from Gold(III)-chelates of β-diketones

    Science.gov (United States)

    Kundu, Subrata; Pal, Anjali; Ghosh, Sujit Kumar; Nath, Sudip; Panigrahi, Sudipa; Praharaj, Snigdhamayee; Basu, Soumen; Pal, Tarasankar

    2005-12-01

    Chelating ligands with β-diketone skeleton have been employed for the first time as reductant to produce ligand stabilized gold nanoparticles of different shapes out of aqueous HAuCl4 solutions. Evolution of stable gold nanoparticles happens to be first order with respect to gold particles having rate constants ˜ ˜10-2 min-1 and subsequent chlorine insertion in the β-diketone skeleton is reported as a general feature. Spherical or triangular or hexagonal particle evolution goes selectively under the influence of different β-diketones in terms of capping and reducing capabilities of the reductants.

  4. Shape-controlled Synthesis of Gold Nanoparticles from Gold(III)-chelates of {beta}-diketones

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Subrata [Indian Institute of Technology, Department of Chemistry (India); Pal, Anjali [Indian Institute of Technology, Department of Civil Engineering (India); Ghosh, Sujit Kumar; Nath, Sudip; Panigrahi, Sudipa; Praharaj, Snigdhamayee; Basu, Soumen; Pal, Tarasankar [Indian Institute of Technology, Department of Chemistry (India)], E-mail: tpal@chem.iitkgp.ernet.in

    2005-12-15

    Chelating ligands with {beta}-diketone skeleton have been employed for the first time as reductant to produce ligand stabilized gold nanoparticles of different shapes out of aqueous HAuCl{sub 4} solutions. Evolution of stable gold nanoparticles happens to be first order with respect to gold particles having rate constants {approx}{approx}10{sup -2} min{sup -1} and subsequent chlorine insertion in the {beta}-diketone skeleton is reported as a general feature. Spherical or triangular or hexagonal particle evolution goes selectively under the influence of different {beta}-diketones in terms of capping and reducing capabilities of the reductants.

  5. Oxidation of Bioethanol using Zeolite-Encapsulated Gold Nanoparticles

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Abildstrøm, Jacob Oskar; Wang, Feng

    2014-01-01

    With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite‐1 is reported and their high...... zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2–3 nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50 % conversion of ethanol with 98...

  6. Oxidation of Bioethanol using Zeolite-Encapsulated Gold Nanoparticles

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Abildstrøm, Jacob Oskar; Wang, Feng

    2014-01-01

    With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite-1 is reported and their high...... zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2-3nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50% conversion of ethanol with 98...

  7. Optical manipulation of gold nanoparticles using an optical nanofiber

    Institute of Scientific and Technical Information of China (English)

    Li Ying; Hu Yan-Jun

    2013-01-01

    Gold nanoparticles are gaining increasing attention due to their biological and medical applications.In this letter,we experimentally demonstrate the optical manipulation of 250-nm-diameter gold nanoparticles along an optical nanofiber (550 nm in diameter) injected by an 808-nm laser light.The nanoparticles situated in the evanescent optical field are trapped by optical gradient force and move along the direction of light propagation due to optical scattering force.The velocities reach as high as 132 μm/s at an optical power of 80 mW.

  8. Vibrational properties of gold nanoparticles obtained by green synthesis

    Science.gov (United States)

    Alvarez, Ramón A. B.; Cortez-Valadez, M.; Bueno, L. Oscar Neira; Britto Hurtado, R.; Rocha-Rocha, O.; Delgado-Beleño, Y.; Martinez-Nuñez, C. E.; Serrano-Corrales, Luis Ivan; Arizpe-Chávez, H.; Flores-Acosta, M.

    2016-10-01

    This study reports the synthesis and characterization of gold nanoparticles through an ecological method to obtain nanostructures from the extract of the plant Opuntia ficus-indica. Colloidal nanoparticles show sizes that vary between 10-20 nm, and present various geometric morphologies. The samples were characterized through optical absorption, Raman Spectroscopy and Transmission Electron Microscopy (TEM). Additionally, low energy metallic clusters of Aun (n=2-20 atoms) were modeled by computational quantum chemistry. The theoretical results were obtained with Density Functional Theory (DFT). The predicted results of Au clusters show a tendency and are correlated with the experimental results concerning the optical absorption bands and Raman spectroscopy in gold nanoparticles.

  9. Green synthesis of size controllable gold nanoparticles

    Science.gov (United States)

    Mohan Kumar, Kesarla; Mandal, Badal Kumar; Kiran Kumar, Hoskote A.; Maddinedi, Sireesh Babu

    2013-12-01

    A facile rapid green eco-friendly method to synthesize gold nanoparticles (Au NPs) of tunable size using aqueous Terminalia arjuna fruit extracts has been demonstrated herein. Formation of Au NPs was confirmed by Surface Plasmon Resonance (SPR) study at 528 nm using UV-visible spectrophotometer. The time of reduction, size and morphological variations of Au NPs were studied with varying quantities of T. arjuna fruit aqueous extracts. Synthesized Au NPs were characterized using UV-visible spectroscopy, Fourier transformed infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscopy (EDAX). Polyphenols responsible for reduction of Au3+ to Au0 were identified using High Performance Liquid Chromatography (HPLC) as ascorbic acid, gallic acid and pyrogallol. The oxidized forms of polyphenols formed coordination with surface of Au NPs which protected their further growth and aggregation. We also propose a plausible mechanism how to tune size and shape of Au NPs by varying the quantity of extracts. Thus obtained Au NPs were stable for more than four months.

  10. Green synthesis of size controllable gold nanoparticles.

    Science.gov (United States)

    Mohan Kumar, Kesarla; Mandal, Badal Kumar; Kiran Kumar, Hoskote A; Maddinedi, Sireesh Babu

    2013-12-01

    A facile rapid green eco-friendly method to synthesize gold nanoparticles (Au NPs) of tunable size using aqueous Terminalia arjuna fruit extracts has been demonstrated herein. Formation of Au NPs was confirmed by Surface Plasmon Resonance (SPR) study at 528 nm using UV-visible spectrophotometer. The time of reduction, size and morphological variations of Au NPs were studied with varying quantities of T. arjuna fruit aqueous extracts. Synthesized Au NPs were characterized using UV-visible spectroscopy, Fourier transformed infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscopy (EDAX). Polyphenols responsible for reduction of Au(3+) to Au(0) were identified using High Performance Liquid Chromatography (HPLC) as ascorbic acid, gallic acid and pyrogallol. The oxidized forms of polyphenols formed coordination with surface of Au NPs which protected their further growth and aggregation. We also propose a plausible mechanism how to tune size and shape of Au NPs by varying the quantity of extracts. Thus obtained Au NPs were stable for more than four months.

  11. Gold Nanoparticles Inhibit Matrix Metalloproteases without Cytotoxicity.

    Science.gov (United States)

    Hashimoto, M; Sasaki, J I; Yamaguchi, S; Kawai, K; Kawakami, H; Iwasaki, Y; Imazato, S

    2015-08-01

    Nanoparticles (NPs) are currently the focus of considerable attention for dental applications; however, their biological effects have not been fully elucidated. The long-term, slow release of matrix metalloproteases (MMPs) digests collagen fibrils within resin-dentin bonds. Therefore, MMP inhibitors can prolong the durability of resin-dentin bonds. However, there have been few reports evaluating the combined effect of MMP inhibition and the cytotoxic effects of NPs for dentin bonding. The aim of this study was to evaluate MMP inhibition and cytotoxic responses to gold (AuNPs) and platinum nanoparticles (PtNPs) stabilized by polyvinylpyrrolidone (PVP) in cultured murine macrophages (RAW264) by using MMP inhibition assays, measuring cell viability and inflammatory responses (quantitative reverse transcription polymerase chain reaction [RT-qPCR]), and conducting a micromorphological analysis by fluorescence and transmission electron microscopy. Cultured RAW264 cells were exposed to metal NPs at various concentrations (1, 10, 100, and 400 µg/mL). AuNPs and PtNPs markedly inhibited MMP-8 and MMP-9 activity. Although PtNPs were cytotoxic at high concentrations (100 and 400 µg/mL), no cytotoxic effects were observed for AuNPs at any concentration. Transmission electron microscopy images showed a significant nonrandom intercellular distribution for AuNPs and PtNPs, which were mostly observed to be localized in lysosomes but not in the nucleus. RT-qPCR analysis demonstrated inflammatory responses were not induced in RAW264 cells by AuNPs or PtNPs. The cytotoxicity of nanoparticles might depend on the core metal composition and arise from a "Trojan horse" effect; thus, MMP inhibition could be attributed to the surface charge of PVP, which forms the outer coating of NPs. The negative charge of the surface coating of PVP binds to Zn(2+) from the active center of MMPs by chelate binding and results in MMP inhibition. In summary, AuNPs are attractive NPs that effectively

  12. Microwave absorption properties of gold nanoparticle doped polymers

    DEFF Research Database (Denmark)

    Jiang, Chenhui; Ouattara, Lassana; Ingrosso, Chiara

    2011-01-01

    This paper presents a method for characterizing microwave absorption properties of gold nanoparticle doped polymers. The method is based on on-wafer measurements at the frequencies from 0.5GHz to 20GHz. The on-wafer measurement method makes it possible to characterize electromagnetic (EM) property...... of small volume samples. The epoxy based SU8 polymer and SU8 doped with gold nanoparticles are chosen as the samples under test. Two types of microwave test devices are designed for exciting the samples through electrical coupling and magnetic coupling, respectively. Measurement results demonstrate...... that the nanocomposites absorb a certain amount of microwave energy due to gold nanoparticles. Higher nanoparticle concentration results in more significant absorption effect....

  13. Functionalized gold nanoparticles manifested as potent carriers for nucleolar targeting

    Science.gov (United States)

    Shahbazi, Reza; Ozcicek, Ilyas; Ozturk, Gurkan; Ulubayram, Kezban

    2017-01-01

    It is generally known that gold nanoparticles are localised in the cytoplasm and, if synthesised in small sizes or functionalized with specific proteins, they enter the cell nucleus. However, there is no report emphasising the importance of surface functionalization in their accumulation in the nucleolus. Here, for the first time in the literature, it is proposed that functionalization of gold nanoparticles with a thin layer of polyethyleneimine (PEI) spearheads them to the nucleolus of hard-to-transfect post-mitotic dorsal root ganglion neurones in a size-independent manner. As a potential for theranostic applications, it was found that functionalization with a thin layer of PEI affected the emission signal intensity of gold nanoparticles so that the cellular biodistribution of nanoparticles was visualised clearly under both confocal and two-photon microscopes.

  14. Dynamic light scattering on bioconjugated laser generated gold nanoparticles.

    Science.gov (United States)

    Zimbone, Massimo; Baeri, Pietro; Calcagno, Lucia; Musumeci, Paolo; Contino, Annalinda; Barcellona, Maria Luisa; Bonaventura, Gabriele

    2014-01-01

    Gold nanoparticles (AuNPs) conjugated to DNA are widely used for biomedical targeting and sensing applications. DNA functionalization is easily reached on laser generated gold nanoparticles because of their unique surface chemistry, not reproducible by other methods. In this context, we present an extensive investigation concerning the attachment of DNA to the surface of laser generated nanoparticles using Dynamic Light Scattering and UV-Vis spectroscopy. The DNA conjugation is highlighted by the increase of the hydrodynamic radius and by the UV-Vis spectra behavior. Our investigation indicates that Dynamic Light Scattering is a suitable analytical tool to evidence, directly and qualitatively, the binding between a DNA molecule and a gold nanoparticle, therefore it is ideal to monitor changes in the conjugation process when experimental conditions are varied.

  15. Dynamic light scattering on bioconjugated laser generated gold nanoparticles.

    Directory of Open Access Journals (Sweden)

    Massimo Zimbone

    Full Text Available Gold nanoparticles (AuNPs conjugated to DNA are widely used for biomedical targeting and sensing applications. DNA functionalization is easily reached on laser generated gold nanoparticles because of their unique surface chemistry, not reproducible by other methods. In this context, we present an extensive investigation concerning the attachment of DNA to the surface of laser generated nanoparticles using Dynamic Light Scattering and UV-Vis spectroscopy. The DNA conjugation is highlighted by the increase of the hydrodynamic radius and by the UV-Vis spectra behavior. Our investigation indicates that Dynamic Light Scattering is a suitable analytical tool to evidence, directly and qualitatively, the binding between a DNA molecule and a gold nanoparticle, therefore it is ideal to monitor changes in the conjugation process when experimental conditions are varied.

  16. Comparison of amino acids interaction with gold nanoparticle.

    Science.gov (United States)

    Ramezani, Fatemeh; Amanlou, Massoud; Rafii-Tabar, Hashem

    2014-04-01

    The study of nanomaterial/biomolecule interface is an important emerging field in bionanoscience, and additionally in many biological processes such as hard-tissue growth and cell-surface adhesion. To have a deeper understanding of the amino acids/gold nanoparticle assemblies, the adsorption of these amino acids on the gold nanoparticles (GNPs) has been investigated via molecular dynamics simulation. In these simulations, all the constituent atoms of the nanoparticles were considered to be dynamic. The geometries of amino acids, when adsorbed on the nanoparticle, were studied and their flexibilities were compared with one another. The interaction of each of 20 amino acids was considered with 3 and 8 nm gold GNPs.

  17. Self-assembled gold nanoparticles on functionalized gold(111) studied by scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    PENG, Zhang-Quan; WANG, Er-Kang

    2000-01-01

    Nanogold colloidal solutions are prepared by the reduction of HAuClO4 with sodium citrate and sodium borohydride. 4- Aminothiophenol (ATP) self-assembled monolayers (SAMs) are formed on gold(111) surface, on which gold nanoparticles are immobilized and a sub-monolayer of the particles appears. This sub-monolayer of gold nanoparticles is characterized with scanning tunneling microscopy (STM), and a dual energy barrier tunneling model is proposed to explain the imgeability of the gold nanoparticles by STM. This model can also be used to construct multiple energy barrier structure on solid/ liquid interface and to evaluate the electron transport ability of some organic monolayers with the aid of electrochemical method.

  18. Biosynthesis of Gold Nanoparticles (Green-gold Using Leaf Extract of Terminalia Catappa

    Directory of Open Access Journals (Sweden)

    Balaprasad Ankamwar

    2010-01-01

    Full Text Available The synthesis of eco-friendly nanoparticles is evergreen branch of nanoscience for biomedical application. Low cost of synthesis and non toxicity are main features make it more attractive potential option for biomedical field and elsewhere. Here, we report the synthesis of gold nanoparticles in aqueous medium using Terminalia catappa (Almond leaf extract as the reducing and stabilizing agent. On treating chloroauric acid solutions with Terminalia catappa (TC leaf extract rapid reduction of chloroaurate ions is observed leading to the formation of highly stable gold nanoparticles in solution. TEM analysis of the gold nanoparticles indicated that they ranged in size from 10 to 35 nm with average size of 21.9 nm.

  19. MOLECULAR DYNAMICS SIMULATION AND EXPERIMENTAL STUDIES OF GOLD NANOPARTICLE TEMPLATED HDL-LIKE NANOPARTICLES FOR CHOLESTEROL (POSTPRINT)

    Science.gov (United States)

    2016-12-21

    AFRL-RX-WP-JA-2017-0193 MOLECULAR DYNAMICS SIMULATION AND EXPERIMENTAL STUDIES OF GOLD NANOPARTICLE TEMPLATED HDL-LIKE NANOPARTICLES ...SIMULATION AND EXPERIMENTAL STUDIES OF GOLD NANOPARTICLE TEMPLATED HDL-LIKE NANOPARTICLES FOR CHOLESTEROL (POSTPRINT) 5a. CONTRACT NUMBER FA8650-15-2...removing excess cholesterol from arterial plaques. Gold nanoparticles (AuNPs) functionalized with apolipoprotein A-I and with the lipids 1,2

  20. Gold nanoparticle trapping and delivery for therapeutic applications

    Directory of Open Access Journals (Sweden)

    Aziz MS

    2011-12-01

    Full Text Available MS Aziz1, Nathaporn Suwanpayak3,4, Muhammad Arif Jalil2, R Jomtarak4, T Saktioto2, Jalil Ali1, PP Yupapin41Institute of Advanced Photonics Science, 2Ibnu Sina Institute of Fundamental Science Studies, Nanotechnology Research Alliance, Universiti Teknologi Malaysia, Johor Bahru, Malaysia; 3King Mongkut's Institute of Technology Ladkrabang, Chump on Campus, Chumphon, 4Nanoscale Science and Engineering Research Alliance (N'SERA, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok, ThailandAbstract: A new optical trapping design to transport gold nanoparticles using a PANDA ring resonator system is proposed. Intense optical fields in the form of dark solitons controlled by Gaussian pulses are used to trap and transport nanoscopic volumes of matter to the desired destination via an optical waveguide. Theoretically, the gradient and scattering forces are responsible for this trapping phenomenon, where in practice such systems can be fabricated and a thin-film device formed on the specific artificial medical materials, for instance, an artificial bone. The dynamic behavior of the tweezers can be tuned by controlling the optical pulse input power and parameters of the ring resonator system. Different trap sizes can be generated to trap different gold nanoparticles sizes, which is useful for gold nanoparticle therapy. In this paper, we have shown the utility of gold nanoparticle trapping and delivery for therapy, which may be useful for cosmetic therapy and related applications.Keywords: gold nanoparticle trapping, particle trapping, therapy, transport

  1. Tumor necrosis factor interaction with gold nanoparticles

    Science.gov (United States)

    Tsai, De-Hao; Elzey, Sherrie; Delrio, Frank W.; Keene, Athena M.; Tyner, Katherine M.; Clogston, Jeffrey D.; Maccuspie, Robert I.; Guha, Suvajyoti; Zachariah, Michael R.; Hackley, Vincent A.

    2012-05-01

    We report on a systematic investigation of molecular conjugation of tumor necrosis factor-α (TNF) protein onto gold nanoparticles (AuNPs) and the subsequent binding behavior to its antibody (anti-TNF). We employ a combination of physical and spectroscopic characterization methods, including electrospray-differential mobility analysis, dynamic light scattering, polyacrylamide gel electrophoresis, attenuated total reflectance-Fourier transform infrared spectroscopy, fluorescence assay, and enzyme-linked immunosorbent assay. The native TNF used in this study exists in the active homotrimer configuration prior to conjugation. After binding to AuNPs, the maximum surface density of TNF is (0.09 +/- 0.02) nm-2 with a binding constant of 3 × 106 (mol L-1)-1. Dodecyl sulfate ions induce desorption of monomeric TNF from the AuNP surface, indicating a relatively weak intermolecular binding within the AuNP-bound TNF trimers. Anti-TNF binds to both TNF-conjugated and citrate-stabilized AuNPs, showing that non-specific binding is significant. Based on the number of anti-TNF molecules adsorbed, a substantially higher binding affinity was observed for the TNF-conjugated surface. The inclusion of thiolated polyethylene glycol (SH-PEG) on the AuNPs inhibits the binding of anti-TNF, and the amount of inhibition is related to the number ratio of surface bound SH-PEG to TNF and the way in which the ligands are introduced. This study highlights the challenges in quantitatively characterizing complex hybrid nanoscale conjugates, and provides insight on TNF-AuNP formation and activity.We report on a systematic investigation of molecular conjugation of tumor necrosis factor-α (TNF) protein onto gold nanoparticles (AuNPs) and the subsequent binding behavior to its antibody (anti-TNF). We employ a combination of physical and spectroscopic characterization methods, including electrospray-differential mobility analysis, dynamic light scattering, polyacrylamide gel electrophoresis

  2. Collagen-Gold Nanoparticle Conjugates for Versatile Biosensing

    Directory of Open Access Journals (Sweden)

    Sarah Unser

    2017-02-01

    Full Text Available Integration of noble metal nanoparticles with proteins offers promising potential to create a wide variety of biosensors that possess both improved selectivity and versatility. The multitude of functionalities that proteins offer coupled with the unique optical properties of noble metal nanoparticles can allow for the realization of simple, colorimetric sensors for a significantly larger range of targets. Herein, we integrate the structural protein collagen with 10 nm gold nanoparticles to develop a protein-nanoparticle conjugate which possess the functionality of the protein with the desired colorimetric properties of the nanoparticles. Applying the many interactions that collagen undergoes in the extracellular matrix, we are able to selectively detect both glucose and heparin with the same collagen-nanoparticle conjugate. Glucose is directly detected through the cross-linking of the collagen fibrils, which brings the attached nanoparticles into closer proximity, leading to a red-shift in the LSPR frequency. Conversely, heparin is detected through a competition assay in which heparin-gold nanoparticles are added to solution and compete with heparin in the solution for the binding sites on the collagen fibrils. The collagen-nanoparticle conjugates are shown to detect both glucose and heparin in the physiological range. Lastly, glucose is selectively detected in 50% mouse serum with the collagen-nanoparticle devices possessing a linear range of 3–25 mM, which is also within the physiologically relevant range.

  3. Microbial mediated preparation, characterization and optimization of gold nanoparticles.

    Science.gov (United States)

    Barabadi, Hamed; Honary, Soheila; Ebrahimi, Pouneh; Mohammadi, Milad Ali; Alizadeh, Ahad; Naghibi, Farzaneh

    2014-01-01

    The need for eco-friendly and cost effective methods for nanoparticles synthesis is developing interest in biological approaches which are free from the use of toxic chemicals as byproducts. This study aimed to biosynthesize and optimize the size of gold nanoparticles which produced by biotechnological method using Penicillium crustosum isolated from soil. Initially, Penicillium crustosum was grown in fluid czapek dox broth on shaker at 28 °C and 200 rpm for ten days and then the supernatant was separated from the mycelia to convert AuCl₄ solution into gold nanoparticles. The synthesized nanoparticles in the optimum conditions were formed with fairly well-defined dimensions and good monodispersity. The characterizations were done by using different methods (UV-Visible Spectroscopy, Fluorescence, FT-IR, AFM (Atomic Force Microscopy) and DLS (Dynamic Light Scattering). The bioconversion was optimized by Box-Behnken experimental design. The results show that the effective factors in this process were concentration of AuCl₄, pH of medium and temperature of shaker incubator. The R(2) value was calculated to be 0.9999 indicating the accuracy and ability of the polynomial model. It can be concluded that the use of multivariate analysis facilitated to find out the optimum conditions for the biosynthesis of gold nanoparticles induced by Penicillium crustosum in a time and cost effective process. The current approach suggested that rapid synthesis of gold nanoparticles would be suitable for developing a biological process for mass scale production of formulations.

  4. Coassembly of gold nanoparticles and cellulose nanocrystals in composite films.

    Science.gov (United States)

    Lukach, Ariella; Thérien-Aubin, Héloïse; Querejeta-Fernández, Ana; Pitch, Natalie; Chauve, Grégory; Méthot, Myriam; Bouchard, Jean; Kumacheva, Eugenia

    2015-05-12

    Coassembly of nanoparticles with different size-, shape-, and composition-dependent properties is a promising approach to the design and fabrication of functional materials and devices. This paper reports the results of a detailed investigation of the formation and properties of free-stranding composite films formed by the coassembly of cellulose nanocrystals and shape-isotropic plasmonic gold nanoparticles. The effect of gold nanoparticle size, surface charge, and concentration on the structural and optical properties of the composite films has been studied. The composite films retained photonic crystal and chiroptical activity properties. The size and surface charge of gold nanoparticles had a minor effect on the structure and properties of the composite films, while the concentration of gold nanoparticles in the composite material played a more significant role and can be used to fine-tune the optical properties of materials derived from cellulose nanocrystals. These findings significantly broaden the range of nanoparticles that can be used for producing nanocomposite materials based on cellulose nanocrystals. The simplicity of film preparation, the abundance of cellulose nanocrystals, and the robust, free-standing nature of the composite films offer highly advantageous features and pave the way for the generation of functional materials with coupled optical properties.

  5. Microbial mediated preparation, characterization and optimization of gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Hamed Barabadi

    2014-12-01

    Full Text Available The need for eco-friendly and cost effective methods for nanoparticles synthesis is developing interest in biological approaches which are free from the use of toxic chemicals as byproducts. This study aimed to biosynthesize and optimize the size of gold nanoparticles which produced by biotechnological method using Penicillium crustosum isolated from soil. Initially, Penicillium crustosum was grown in fluid czapek dox broth on shaker at 28 ºC and 200 rpm for ten days and then the supernatant was separated from the mycelia to convert AuCl4 solution into gold nanoparticles. The synthesized nanoparticles in the optimum conditions were formed with fairly well-defined dimensions and good monodispersity. The characterizations were done by using different methods (UV-Visible Spectroscopy, Fluorescence, FT-IR, AFM (Atomic Force Microscopy and DLS (Dynamic Light Scattering. The bioconversion was optimized by Box-Behnken experimental design. The results show that the effective factors in this process were concentration of AuCl4, pH of medium and temperature of shaker incubator. The R² value was calculated to be 0.9999 indicating the accuracy and ability of the polynomial model. It can be concluded that the use of multivariate analysis facilitated to find out the optimum conditions for the biosynthesis of gold nanoparticles induced by Penicillium crustosum in a time and cost effective process. The current approach suggested that rapid synthesis of gold nanoparticles would be suitable for developing a biological process for mass scale production of formulations.

  6. Optimization and stabilization of gold nanoparticles by using herbal plant extract with microwave heating

    OpenAIRE

    Yasmin, Akbar; Ramesh, Kumaraswamy; Rajeshkumar, Shanmugam

    2014-01-01

    In this study, we have synthesized the gold nanoparticles by using Hibiscus rosa-sinensis, a medicinal plant. The gold nanoparticles were synthesized rapidly by the involvement of microwave heating. By changing of plant extract concentration, gold solution concentration, microwave heating time and power of microwave heating the optimized condition was identified. The surface Plasmon resonance found at 520 nm confirmed the gold nanoparticles synthesis. The spherical sized nanoparticles in the ...

  7. Synthesis of Gold Nanoparticles Dispersed in Palm Oil Using Laser Ablation Technique

    Directory of Open Access Journals (Sweden)

    Amir Reza Sadrolhosseini

    2017-01-01

    Full Text Available Gold nanoparticles have more applications in biology, medicine, and industry. In this study, gold nanoparticles were synthesized in pure palm oil using laser ablation technique. Gold nanoparticles were fabricated in different temperature, and the effect of the temperature on the particle size was investigated. Consequently, the tail of the carbonyl band of fatty acids was capped gold nanoparticles, and spherically shaped gold nanoparticles with size range of 8.92 to 19.73 nm were formed in palm oil. The temperature caused the agglomeration of nanoparticles while the particle size increased with an increase in the temperature.

  8. Femtosecond laser generated gold nanoparticles and their plasmonic properties

    Science.gov (United States)

    Das, Rupali; Navas M., P.; Soni, R. K.

    2016-05-01

    The pulsed laser ablation in liquid medium is now commonly used to generate stable colloidal nanoparticles (NPs) in absence of any chemical additives or stabilizer with diverse applications. In this paper, we report generation of gold NPs (Au NPs) by ultra-short laser pulses. Femtosecond (fs) laser radiation (λ = 800 nm) has been used to ablate a gold target in pure de-ionized water to produce gold colloids with smallsize distribution. The average size of the particles can be further controlled by subjecting to laser-induced post-irradiation providing a versatile physical method of size-selected gold nanoparticles. The optical extinction and morphological dimensions were investigated with UV-Vis spectroscopy and Transmission Electron Microscopy measurements, respectively. Finite difference time domain (FDTD) method is employed to calculate localized surface plasmon (LSPR) wavelength and the near-field generated by Au NPs and their hybrids.

  9. Separation of Aminobenzoic Acids by Gold Nanoparticle modified Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    YAN,Hongtao; LI,Tuo; GUO,Yanli

    2009-01-01

    A novel method for the separation of aminobenzoic acids by capillary electrophoresis was developed.The capillary was modified with gold nanoparticles.The effect of gold nanoparticles on the resolution and selectivity of separation was investigated.The influence of separation voltage,pH and buffer concentration on the separation of aminobenzoic acids was also examined.It was found that the presence of gold nanoparticles improved the precision of the analysis and increased the separation efficiency.Under the optimized experiment conditions,aminobenzoic acids were separated and determined.Linearity was established over the concentration range 0.5-40 μg·mL-1 with correlation coefficients of 0.9978-0.9992.The detection limits (S/N = 3) were from 0.1 to 0.5 μg·mL-1.

  10. Gold nanoparticle-based microfluidic sensor for mercury detection

    DEFF Research Database (Denmark)

    Lafleur, Josiane P.; Jensen, Thomas Glasdam; Kutter, Jörg Peter

    2011-01-01

    The contamination of natural resources by human activity can have severe socio-economical impacts. Conventional methods of environmental analysis can be significantly improved by the development of portable microscale technologies for remote/field sensing. A gold nanoparticle-based lab-on-a-chip ......The contamination of natural resources by human activity can have severe socio-economical impacts. Conventional methods of environmental analysis can be significantly improved by the development of portable microscale technologies for remote/field sensing. A gold nanoparticle-based lab......-on-a-chip device was developed for the rapid, in-field detection and quantification of mercury in aquatic environments. Rhodamine 6G functionalized gold nanoparticles allowed the on-chip fluorescence detection of mercury in aqueous samples with a limit of detection of 7 nM....

  11. Natural polysaccharide functionalized gold nanoparticles as biocompatible drug delivery carrier.

    Science.gov (United States)

    Pooja, Deep; Panyaram, Sravani; Kulhari, Hitesh; Reddy, Bharathi; Rachamalla, Shyam S; Sistla, Ramakrishna

    2015-09-01

    Biocompatibility is one of the major concerns with inorganic nanoparticles for their applications as drug delivery system. Natural compounds such as sugars, hydrocolloids and plant extracts have shown potential for the green synthesis of biocompatible gold nanoparticles. In this study, we report the synthesis of gum karaya (GK) stabilized gold nanoparticles (GKNP) and the application of prepared nanoparticles in the delivery of anticancer drugs. GKNP were characterized using different analytical techniques. GKNP exhibited high biocompatibility during cell survival study against CHO normal ovary cells and A549 human non-small cell lung cancer cells and during hemolytic toxicity studies. Gemcitabine hydrochloride (GEM), an anticancer drug, was loaded on the surface of nanoparticles with 19.2% drug loading efficiency. GEM loaded nanoparticles (GEM-GNP) showed better inhibition of growth of cancer cells in anti-proliferation and clonogenic assays than native GEM. This effect was correlated with higher reactive oxygen species generation by GEM-GNP in A549 cells than native GEM. In summary, GK has significant potential in the synthesis of biocompatible gold nanoparticles that could be used as prospective drug delivery carrier for anticancer drugs.

  12. Biochemical synthesis of gold and zinc nanoparticles in reverse micelles

    Science.gov (United States)

    Egorova, E. M.

    2010-04-01

    Gold and zinc nanoparticles were obtained in AOT reverse micelles in isooctane by reduction of the corresponding metal ions by the natural pigment quercetin (the biochemical synthesis technique). Gold and zinc ions were introduced into the micellar solution of quercetin in the form of aqueous solutions, HAuCl4 and [Zn(NH3)4]SO4, to the water to AOT molar ratios 1-3 and 3-4, respectively. The process of nanoparticle formation was investigated by spectrophotometry. Nanoparticle size and shape were determined by transmission electron microscopy. The data obtained allow to conclude that there are two steps in metal ion-quercetin interaction: (1) complex formation, and (2) complex dissociation with subsequent formation of nanoparticles and a second product, presumably oxidized quercetin. Gold nanoparticles were found to be of various shapes (spheres, hexahedrons, triangles, and cylinders) and sizes, mainly in the 10-20 nm range; zinc nanoparticles are chiefly spherical and ˜5 nm in size. In both cases, the nanoparticles are stable in the air in micellar solution over long periods of time (from a several months to a several years).

  13. Xanthan gum stabilized gold nanoparticles: characterization, biocompatibility, stability and cytotoxicity.

    Science.gov (United States)

    Pooja, Deep; Panyaram, Sravani; Kulhari, Hitesh; Rachamalla, Shyam S; Sistla, Ramakrishna

    2014-09-22

    Xanthan gum (XG) has been widely used in food, pharmaceutical and cosmetic industries. In the present study, we explored the potential of XG in the synthesis of gold nanoparticle. XG was used as both reducing and stabilizing agent. The effect of various formulation and process variables such as temperature, reaction time, gum concentration, gum volume and gold concentration, in GNP preparation was determined. The XG stabilized, rubey-red XGNP were obtained with 5 ml of XG aqueous solution (1.5 mg/ml). The optimum temperature was 80°C whereas the reaction time was 3 h. The optimized nanoparticles were also investigated as drug delivery carrier for doxorubicin hydrochloride. DOX loaded gold nanoparticles (DXGP) were characterized by dynamic light scattering, TEM, FTIR, and DSC analysis. The synthesized nanoparticle showed mean particle size of 15-20 nm and zeta potential -29.1 mV. The colloidal stability of DXGP was studied under different conditions of pH, electrolytes and serum. Nanoparticles were found to be stable at pH range between pH 5-9 and NaCl concentration up to 0.5 M. In serum, nanoparticles showed significant stability up to 24h. During toxicity studies, nanoparticles were found biocompatible and non-toxic. Compared with free DOX, DXGP displayed 3 times more cytotoxicity in A549 cells. In conclusion, this study provided an insight to synthesize GNP without using harsh chemicals.

  14. Hydrophobic properties of a fluoropolymer film covering gold nanoparticles

    Science.gov (United States)

    Safonov, A. I.; Starinskii, S. V.; Sulyaeva, V. S.; Timoshenko, N. I.; Gatapova, E. Ya.

    2017-02-01

    Thin fluoropolymer films were deposited on gold nanoparticles with different diameters by the hot-wire chemical-vapor-deposition method. The contact angles of wetting of samples with water and CH2I2 were determined using a DSA-100 KRUSS device, and the free surface energy of the coated surface was also determined. The influence of encapsulated gold particles on the hydrophobic properties of the obtained coatings was determined.

  15. Preparation of 2 nm gold nanoparticles for in vitro and in vivo applications

    OpenAIRE

    Moyano, Daniel F.; Duncan, Bradley; Rotello, Vincent M.

    2013-01-01

    Gold nanoparticles have been a versatile tool in recent years for the exploration of biological systems. However, challenges with purification and adequate surface coverage limit the biocompatibility of gold nanoparticles. Here, we describe a detailed procedure for the synthesis, purification, and functionalization of biologically compatible gold nanoparticles for in vitro and in vivo studies.

  16. Influence of gold nanoparticles on platelets functional activity in vitro

    Science.gov (United States)

    Akchurin, Garif G.; Akchurin, George G.; Ivanov, Alexey N.; Kirichuk, Vyacheslav F.; Terentyuk, George S.; Khlebtsov, Boris N.; Khlebtsov, Nikolay G.

    2008-02-01

    Now in the leading biomedical centers of the world approved new technology of laser photothermal destruction of cancer cells using plasmon gold nanoparticles. Investigations of influence of gold nanoparticles on white rat platelets aggregative activity in vitro have been made. Platelet aggregation was investigated in platelet rich plasma (PRP) with help of laser analyzer 230 LA >, Russia). Aggregation inductor was ADP solution in terminal concentration 2.5 micromole (>, Russia). Gold nanoshells soluted in salt solution were used for experiments. Samples of PRP were incubated with 50 or 100 μl gold nanoshells solution in 5 minute, after that we made definition ADP induced platelet aggregation. We found out increase platelet function activity after incubation with nanoparticles solution which shown in maximum ADP-induced aggregation degree increase. Increase platelet function activity during intravenous nanoshells injection can be cause of thrombosis on patients. That's why before clinical application of cancer cell destruction based on laser photothermal used with plasmon gold nanoparticles careful investigations of thrombosis process and detail analyze of physiological blood parameters are very necessary.

  17. In situgrowth of gold nanoparticles on latent fingerprints--from forensic applications to inkjet printed nanoparticle patterns

    Science.gov (United States)

    Hussain, Irshad; Hussain, Syed Zajif; Habib-Ur-Rehman, Affa; Ihsan, Ayesha; Rehman, Asma; Khalid, Zafar M.; Brust, Mathias; Cooper, Andrew I.

    2010-12-01

    Latent fingerprints are made visible in a single step by in situgrowth of gold nanoparticles on ridge patterns. The chemicals, among the essential components of human sweat, found responsible for the formation and assembly of gold nanoparticles are screened and used as ink to write invisible patterns, using common ball pen and inkjet printer, which are then developed by selectively growing gold nanoparticles by soaking them in gold salt solution.Latent fingerprints are made visible in a single step by in situgrowth of gold nanoparticles on ridge patterns. The chemicals, among the essential components of human sweat, found responsible for the formation and assembly of gold nanoparticles are screened and used as ink to write invisible patterns, using common ball pen and inkjet printer, which are then developed by selectively growing gold nanoparticles by soaking them in gold salt solution. Electronic supplementary information (ESI) available: Detailed experimental procedure and some supporting images. See DOI: 10.1039/c0nr00593b

  18. Manganese oxides supported on gold nanoparticles: new findings and current controversies for the role of gold.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi; Hosseini, Seyedeh Maedeh; Hołyńska, Małgorzata; Tomo, Tatsuya; Allakhverdiev, Suleyman I

    2015-12-01

    We synthesized manganese oxides supported on gold nanoparticles (diameter gold nanoparticles under hydrothermal conditions. In this green method Mn oxide is deposited on the gold nanoparticles. The compounds were characterized by scanning electron microscopy, energy-dispersive spectrometry, high-resolution transmission electron microscopy, X-ray diffraction, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, and atomic absorption spectroscopy. In the next step, the water-oxidizing activities of these compounds in the presence of cerium(IV) ammonium nitrate as a non-oxo transfer oxidant were studied. The results show that these compounds are good catalysts toward water oxidation with a turnover frequency of 1.0 ± 0.1 (mmol O2/(mol Mn·s)). A comparison with other previously reported Mn oxides and important factors influencing the water-oxidizing activities of Mn oxides is also discussed.

  19. Bio-mediated synthesis, characterization and cytotoxicity of gold nanoparticles.

    Science.gov (United States)

    Klekotko, Magdalena; Matczyszyn, Katarzyna; Siednienko, Jakub; Olesiak-Banska, Joanna; Pawlik, Krzysztof; Samoc, Marek

    2015-11-21

    We report here a "green" approach for the synthesis of gold nanoparticles (GNPs) in which the Mentha piperita extract was applied for the bioreduction of chloroauric acid and the stabilization of the formed nanostructures. The obtained GNPs were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). The reduction of gold ions with the plant extract leads to the production of nanoparticles with various shapes (spherical, triangular and hexagonal) and sizes (from 10 to 300 nm). The kinetics of the reaction was monitored and various conditions of the synthesis were investigated. As a result, we established protocols optimized towards the synthesis of nanospheres and nanoprisms of gold. The cytotoxic effect of the obtained gold nanoparticles was studied by performing MTT assay, which showed lower cytotoxicity of the biosynthesized GNPs compared to gold nanorods synthesized using the usual seed-mediated growth. The results suggest that the synthesis using plant extracts may be a useful method to produce gold nanostructures for various biological and medical applications.

  20. Preparation of DNA/Gold Nanoparticle Encapsulated in Calcium Phosphate

    Directory of Open Access Journals (Sweden)

    Tomoko Ito

    2011-01-01

    Full Text Available Biocompatible DNA/gold nanoparticle complex with a protective calcium phosphate (CaP coating was prepared by incubating DNA/gold nanoparticle complex coated by hyaluronic acid in SBF (simulated body fluid with a Ca concentration above 2 mM. The CaP-coated DNA complex was revealed to have high compatibility with cells and resistance against enzymatic degradation. By immersion in acetate buffer (pH 4.5, the CaP capsule released the contained DNA complex. This CaP capsule including a DNA complex is promising as a sustained-release system of DNA complexes for gene therapy.

  1. Gold nanoparticles in breast cancer treatment: Promise and potential pitfalls

    Science.gov (United States)

    Lee, Jihyoun; Chatterjee, Dev Kumar; Lee, Min Hyuk; Krishnan, Sunil

    2014-01-01

    Despite remarkable achievements in the treatment of breast cancer, some obstacles still remain. Gold nanoparticles may prove valuable in addressing these problems owing to their unique characteristics, including their enhanced permeability and retention in tumor tissue, their light absorbance and surface plasmon resonance in near-infrared light, their interaction with radiation to generate secondary electrons, and their ability to be conjugated with drugs or other agents. Herein, we discuss some basic concepts of gold nanoparticles, and early results from studies regarding their use in breast cancer, including toxicity and side effects. We also discuss these particles’ potential clinical applications. PMID:24556077

  2. Melting Transition of Directly-Linked Gold Nanoparticle DNA Assembly

    CERN Document Server

    Sun, Y; Kiang, C H

    2005-01-01

    DNA melting and hybridization is a fundamental biological process as well as a crucial step in many modern biotechnology applications. DNA confined on surfaces exhibits different behavior from that in free solutions. The system of DNA-capped gold nanoparticles exhibits unique phase transitions and represents a new class of complex fluids. Depending on the sequence of the DNA, particles can be linked to each other through direct complementary DNA sequences or via a ``linker'' DNA whose sequence is complementary to the sequence attached to the gold nanoparticles. We observed different melting transitions for these two distinct systems.

  3. Gold nanoparticle-based microfluidic sensor for mercury detection

    DEFF Research Database (Denmark)

    Lafleur, Josiane P.; Jensen, Thomas Glasdam; Kutter, Jörg Peter

    2011-01-01

    The contamination of natural resources by human activity can have severe socio-economical impacts. Conventional methods of environmental analysis can be significantly improved by the development of portable microscale technologies for remote/field sensing. A gold nanoparticle-based lab-on-a-chip ......-on-a-chip device was developed for the rapid, in-field detection and quantification of mercury in aquatic environments. Rhodamine 6G functionalized gold nanoparticles allowed the on-chip fluorescence detection of mercury in aqueous samples with a limit of detection of 7 nM....

  4. Dynamics of alkyl chains in monolayer protected metal clusters and their superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, R [Solid State Physics Division, BARC, Mumbai 400085 (India); Mitra, S [Solid State Physics Division, BARC, Mumbai 400085 (India); Johnson, M [Institute Lau-Langevin, BP156, F-38042, Grenoble, Cedex 9 (France); Pradeep, T [Department of Chemistry and SAIF, IITm, Chennai 600 036 (India)

    2007-12-15

    Alkyl chains dynamics in monolayer protected metal cluster (MPC) systems of gold and silver have been studied by the quasielastic neutron scattering (QENS) technique. Isolated MPCs investigated are 6, 12 and 18 carbon n-alkyl chain thiolate protected 4 nm diameter gold clusters while the superlattices are their silver analogues. Evolution of dynamics with temperature is found to be very different in the isolated clusters and their superlattices. While continuous evolution of the dynamics of the monolayer was observed in isolated MPCs, it is abrupt in superlattice systems and occurs at a temperature consistent with the superlattice melting detected in calorimetry measurements. A model where the chain undergoes uniaxial rotational diffusion with additional body axis fluctuation was found to describe the data consistently. For the superlattice systems, the chains are found to be held by strong inter-chain interactions below the superlattice melting. The data from the planar silver thiolate systems show similar behavior like the superlattice systems, consistent with the calorimetric data.

  5. Gold nanoparticles for tumour detection and treatment

    NARCIS (Netherlands)

    Hartsuiker, Liesbeth; Petersen, W.; Petersen, Wilhelmina; Jose, J.; Jose, J.; van Es, P.; van Es, Peter; Lenferink, Aufrid T.M.; Poot, Andreas A.; Terstappen, Leonardus Wendelinus Mathias Marie; van Leeuwen, Ton; Manohar, Srirang; Otto, Cornelis

    2011-01-01

    The use of nanoparticles in biomedical applications is emerging rapidly. Recent developments have led to numerous studies of noble metal nanoparticles, down to the level of single molecule detection in living cells. The application of noble metal nanoparticles in diagnostics and treatment of early s

  6. Gold nanoparticles for tumour detection and treatment

    NARCIS (Netherlands)

    Hartsuiker, L.; Petersen, W.; Jose, J.; Es, van P.; Lenferink, A.; Poot, A.A.; Terstappen, L.W.M.M.; Manohar, S.; Otto, C.; Leeuwen, van T.G.

    2011-01-01

    The use of nanoparticles in biomedical applications is emerging rapidly. Recent developments have led to numerous studies of noble metal nanoparticles, down to the level of single molecule detection in living cells. The application of noble metal nanoparticles in diagnostics and treatment of early s

  7. Green synthesis of gold nanoparticles using Nyctanthes arbortristis flower extract.

    Science.gov (United States)

    Das, Ratul Kumar; Gogoi, Nayanmoni; Bora, Utpal

    2011-06-01

    The present study explores the reducing and capping potentials of ethanolic flower extract of the plant Nyctanthes arbortristis for the synthesis of gold nanoparticles. The extract at different volume fractions were stirred with HAuCl4 aqueous solution at 80 °C for 30 min. The UV-Vis spectroscopic analysis of the reaction products confirmed successful reduction of Au(3+) ions to gold nanoparticles. Transmission electron microscope (TEM) revealed dominant spherical morphology of the gold nanoparticles with an average diameter of 19.8 ± 5.0 nm. X-ray diffraction (XRD) study confirmed crystalline nature of the synthesized particles. Fourier transform infra-red (FTIR) and nuclear magnetic resonance (NMR) analysis of the purified and lyophilized gold nanoparticles confirmed the surface adsorption of biomolecules during preparation and caused long-term (6 months) stability. Low reaction temperature (25 °C) favored anisotropy. The strong reducing power of the flower extract can also be tested in the green synthesis of other metallic nanoparticles.

  8. GOLD NANOPARTICLES ENCAPSULATED IN A POLYMERIC MATRIX OF SODIUM ALGINATE

    Directory of Open Access Journals (Sweden)

    Oana Lelia POP

    2016-11-01

    Full Text Available Plasmonic nanoparticles can be used as building blocks for the design of multifunctional systems based on polymeric capsules. The use of functionalised particles in therapeutics and imaging and understanding their effect on the cell functions are among the current challenges in nanobiotechnology and nanomedicine. The aim of the study was to manufacture and characterize polymeric microstructures by encapsulating plasmonic gold nanoparticles in biocompatible matrix of sodium alginate. The gold nanoparticles were obtained by reduction of tetracluoroauric acid with sodium citrate. To characterize the microcapsules, UV-Vis and FTIR spectroscopy, optical and confocal microscopy experiments were performed. In vitro cytotoxicity tests on HFL-1 cells were also performed. The capsules have spherical shape and 120 μm diameter. The presence of encapsulated gold nanoparticles is also shown by confocal microscopy. In vitro tests show that the microcapsules are not cytotoxic upon 24 h of cells exposure to microcapsules concentrations ranging from 2.5 to 25 capsules per cell. The obtained microcapsules of sodium alginate loaded with plasmonic gold nanoparticles could potentially be considered as release systems for biologically relevant molecules.

  9. Carbon nanotubes/laser ablation gold nanoparticles composites

    Energy Technology Data Exchange (ETDEWEB)

    Lascialfari, Luisa [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019 (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Via Giusti 9, Firenze 50123 (Italy); Marsili, Paolo [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019 (Italy); Caporali, Stefano [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Via Giusti 9, Firenze 50123 (Italy); Muniz-Miranda, Maurizio [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Margheri, Giancarlo [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019 (Italy); Serafini, Andrea; Brandi, Alberto [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Giorgetti, Emilia, E-mail: emilia.giorgetti@fi.isc.cnr.it [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019 (Italy); Cicchi, Stefano, E-mail: stefano.cicchi@unifi.it [Department of Chemistry, Università di Firenze, Via della Lastruccia 3-13, Sesto Fiorentino, Firenze 50019 (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Via Giusti 9, Firenze 50123 (Italy)

    2014-10-31

    The production of nanohybrids formed by oxidized multiwalled carbon nanotubes (MWCNTs) and nanoparticles, produced by pulsed laser ablation in liquids process, is described. The use of linkers, obtained by transformation of pyrene-1-butanol, is mandatory to generate an efficient and stable interaction between the two components. Transmission electron microscopy and X-ray photoelectron spectroscopy analysis showed the obtainment of the efficient coverage of the MWCNTs by nanoparticles composed by metal gold and, partially, by oxides. - Highlights: • Laser ablation is a used for the production of gold nanoparticle colloids • An efficient decoration of carbon nanotubes with nanoparticles is obtained through the use of a linker • This method allows an efficient and tunable preparation of carbon nanotube hybrids.

  10. Kinematics of gold nanoparticles manipulation in situ transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Alducin, Diego; Casillas, Gilberto; Mendoza-Santoyo, Fernando; Ponce, Arturo; José-Yacamán, Miguel, E-mail: miguel.yacaman@utsa.edu [University of Texas at San Antonio, Department of Physics and Astronomy (United States)

    2015-05-15

    Nanostructured materials such as nanoparticles, nanotubes, and nanowires are subject to different forces regimes compared with their macroscopic counterparts. In this work, we report the experimental manipulation of an individual gold nanoparticle (96 nm) capped with PVP considering forces surrounding the nanoparticle such as adhesion, friction, and the external load in real time, and how the differences between these forces produce distinct motions. Combining a scanning probe tool within a transmission electron microscope, we manipulated a gold nanoparticle and recorded the sliding and rolling kinematic motions. Our observations show quantitatively the adhesion force, maximum rolling resistance, and friction coefficients of the probe and the surface of the capped particle as well as particle and substrate surface.

  11. Near-field heat transfer between gold nanoparticle arrays

    Energy Technology Data Exchange (ETDEWEB)

    Phan, Anh D., E-mail: anhphan@mail.usf.edu [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi 10000 (Viet Nam); Phan, The-Long, E-mail: ptlong2512@yahoo.com [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Woods, Lilia M. [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States)

    2013-12-07

    The radiative heat transfer between gold nanoparticle layers is presented using the coupled dipole method. Gold nanoparticles are modelled as effective electric and magnetic dipoles interacting via electromagnetic fluctuations. The effect of higher-order multipoles is implemented in the expression of electric polarizability to calculate the interactions at short distances. Our findings show that the near-field radiation reduces as the radius of the nanoparticles is increased. Also, the magnetic dipole contribution to the heat exchange becomes more important for larger particles. When one layer is displayed in parallel with respect to the other layer, the near-field heat transfer exhibits oscillatory-like features due to the influence of the individual nanostructures. Further details about the effect of the nanoparticles size are also discussed.

  12. Monomer adsorption of indocyanine green to gold nanoparticles.

    Science.gov (United States)

    Guerrini, Luca; Hartsuiker, Liesbeth; Manohar, Srirang; Otto, Cees

    2011-10-05

    NIR-dye encoded gold nanoparticles (GNP) are rapidly emerging as contrast agents in many bio-imaging/sensing applications. The coding process is usually carried out without control or a clear understanding of the metal-liquid interface properties which, in contrast, are critical in determining the type and extension of dye-metal interaction. In this paper, we investigated the effect of gold surface composition on the adsorption of indocyanine green (ICG) on GNP, simulating the surface conditions of gold nanorods on citrate-capped gold nanospheres. These substrates allowed a careful control of the metal-liquid interface composition and, thus, detailed absorption and fluorescence concentration studies of the effects of each individual chemical in the colloidal solution (i.e. bromide anions, cetyl trimethylammonium ions and Ag(+) ions) on the ICG-gold interaction. This study reveals the drastic effect that these experimental parameters can have on the ICG adsorption on GNP.

  13. Comparative Aquatic Toxicity of Gold Nanoparticles and Ionic Gold Using a Species Sensitivity Distribution Approach

    Directory of Open Access Journals (Sweden)

    Tarryn L. Botha

    2015-01-01

    Full Text Available Gold nanoparticles (nAu are used in drug delivery systems allowing for targeted cellular distribution. The effects of increased use and release of nanoparticles into the environment are not well known. A species sensitivity distribution (SSD allows for the ecotoxicological hazard assessment of a chemical based on single species toxicity tests. Aquatic toxicity needs to be related to particle characterization in order to understand the effects. The behaviour of nAu in the medium changed as the concentration increased. The toxic potential of ionic gold and nAu was expressed as a hazardous concentration where 5% of species will be harmed (HC5. The HC5 for nAu was much higher (42.78 mg/L compared to the ionic gold (2.44 mg/L. The differences between the hazard potentials of nAu and ionic gold were attributed to the nAu not releasing any Au ions into solution during the exposures and following an aggregation theory response. Exposures to ionic gold on the other hand followed a clear dose dependent response based on the concentration of the ionic metal. Although SSDs present an indication of the relative hazard potential of nanoparticles, the true worth can only be achieved once other nanoparticle characteristics and their behavior in the environment are also considered.

  14. Peptide-functionalized iron oxide magnetic nanoparticle for gold mining

    Science.gov (United States)

    Shen, Wei-Zheng; Cetinel, Sibel; Sharma, Kumakshi; Borujeny, Elham Rafie; Montemagno, Carlo

    2017-02-01

    Here, we present our work on preparing a novel nanomaterial composed of inorganic binding peptides and magnetic nanoparticles for inorganic mining. Two previously selected and well-characterized gold-binding peptides from cell surface display, AuBP1 and AuBP2, were exploited. This nanomaterial (AuBP-MNP) was designed to fulfill the following two significant functions: the surface conjugated gold-binding peptide will recognize and selectively bind to gold, while the magnetic nano-sized core will respond and migrate according to the applied external magnetic field. This will allow the smart nanomaterial to mine an individual material (gold) from a pool of mixture, without excessive solvent extraction, filtration, and concentration steps. The working efficiency of AuBP-MNP was determined by showing a dramatic reduction of gold nanoparticle colloid concentration, monitored by spectroscopy. The binding kinetics of AuBP-MNP onto the gold surface was determined using surface plasmon resonance (SPR) spectroscopy, which exhibits around 100 times higher binding kinetics than peptides alone. The binding capacity of AuBP-MNP was demonstrated by a bench-top mining test with gold microparticles.

  15. Encapsulation of Gold Nanoparticles in a DNA Origami Cage

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhao; Jacovetty, Erica L.; Liu, Yan; Yan, Hao

    2011-01-21

    A critical challenge in nanoparticle (NP) surface functionalization is to label the NP surface with a single copy of a functional group or to display multiple, unique molecules on the NP surface with control of the orientation and intermolecular distance. This challenge was addressed with the construction of a spatially addressable, self-assembling DNA origami nanocage that encapsulates gold nanoparticles and interrupts its surface symmetry

  16. Gold nanoparticle capture within protein crystal scaffolds

    Science.gov (United States)

    Kowalski, Ann E.; Huber, Thaddaus R.; Ni, Thomas W.; Hartje, Luke F.; Appel, Karina L.; Yost, Jarad W.; Ackerson, Christopher J.; Snow, Christopher D.

    2016-06-01

    DNA assemblies have been used to organize inorganic nanoparticles into 3D arrays, with emergent properties arising as a result of nanoparticle spacing and geometry. We report here the use of engineered protein crystals as an alternative approach to biologically mediated assembly of inorganic nanoparticles. The protein crystal's 13 nm diameter pores result in an 80% solvent content and display hexahistidine sequences on their interior. The hexahistidine sequence captures Au25(glutathione)~17 (nitrilotriacetic acid)~1 nanoclusters throughout a chemically crosslinked crystal via the coordination of Ni(ii) to both the cluster and the protein. Nanoparticle loading was validated by confocal microscopy and elemental analysis. The nanoparticles may be released from the crystal by exposure to EDTA, which chelates the Ni(ii) and breaks the specific protein/nanoparticle interaction. The integrity of the protein crystals after crosslinking and nanoparticle capture was confirmed by single crystal X-ray crystallography.DNA assemblies have been used to organize inorganic nanoparticles into 3D arrays, with emergent properties arising as a result of nanoparticle spacing and geometry. We report here the use of engineered protein crystals as an alternative approach to biologically mediated assembly of inorganic nanoparticles. The protein crystal's 13 nm diameter pores result in an 80% solvent content and display hexahistidine sequences on their interior. The hexahistidine sequence captures Au25(glutathione)~17 (nitrilotriacetic acid)~1 nanoclusters throughout a chemically crosslinked crystal via the coordination of Ni(ii) to both the cluster and the protein. Nanoparticle loading was validated by confocal microscopy and elemental analysis. The nanoparticles may be released from the crystal by exposure to EDTA, which chelates the Ni(ii) and breaks the specific protein/nanoparticle interaction. The integrity of the protein crystals after crosslinking and nanoparticle capture was

  17. Antibacterial Activity and Cytotoxicity of Gold (I) and (III) Ions and Gold Nanoparticles

    OpenAIRE

    Shareena Dasari, TP; Zhang, Y; Yu, H.

    2015-01-01

    Gold nanoparticles (AuNPs) and gold ion complexes have been investigated for their antibacterial activities. However, the majority of the reports failed to disclose the concentration of free Au(I) or Au(III) present in solutions of AuNPs or gold ion complexes. The inconsistency of antibacterial activity of AuNPs may be due to the effect of the presence of Au(III). Here we report the antibacterial activity of Au(I) and Au(III) to four different bacteria: one nonpathogenic bacterium: E. coli an...

  18. Fungus-mediated synthesis of gold nanoparticles: a novel biological approach to nanoparticle synthesis.

    Science.gov (United States)

    Honary, Soheyla; Gharaei-Fathabad, Eshrat; Barabadi, Hamed; Naghibi, Farzaneh

    2013-02-01

    The biological effects of nanoparticles and their uses as molecular probes are research areas of growing interest. The present study demonstrates an eco-friendly biosynthesis of gold nanoparticles. The pure colonies of penicillium aurantiogriseum, penicillium citrinum, and penicillium waksmanii were cultured in fluid czapek dox broth. Then, their supernatants were examined for the ability to produce gold nanoparticles. In this step, 1 mM solution of AuCl added to the reaction matrixes separately. The reactions were performed in a dark environment at 28 degrees C. After 24 hours, it was observed that the color of the solutions turned to dark purple from light yellow. Synthesized gold nanoparticles were characterized by using UV-Visible Spectroscopy, Nano Zeta Sizer, Scanning Electron Microscopy and Fourier transformed infrared spectroscopy. The results showed that the gold nanoparticles were formed fairly uniform with spherical shape with the Z-average diameter of 153.3 nm, 172 nm and 160.1 nm for penicillium aurantiogriseum, penicillium citrinum, and penicillium waksmanii, respectively. The Fourier transformed infrared spectra revealed the presence of different functional groups to gold nanoparticles which were present in the fungal extract. The current approach suggests that the rapid synthesis of nanoparticles would be proper for developing a biological process for mass scale production.

  19. Reaction parameters for controlled sonosynthesis of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez M, A. L. [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Paseo Colon esq. Paseo Tollocan s/n, 50120 Toluca, Estado de Mexico (Mexico); Cabrera L, L. I. [UNAM-UAEM, Centro Conjunto de Investigacion en Quimica Sustentable, Km 14.5 Carretera Toluca-Atlacomulco, 50200 San Cayetano-Toluca, Estado de Mexico (Mexico)

    2015-07-01

    The synthesis of gold nanoparticles by sonochemical technique has been previously performed with excellent results. The synthesis has been carried out in the presence of citric acid, a strong reducing agent, which allows the nucleation and growth of gold nanoparticles, at the same time that controls particle size. In this work we report the use of sodium tartrate as a mild reducing agent that allows a better understanding of the effect of the reaction parameters during gold nanoparticle synthesis. A conventional sonication bath (37 k Hz) was used for the sonochemical synthesis. This work focuses on the reaction temperature effect and the effect of sodium tartrate concentration. It was confirmed that particle size, and particle morphology is dependent of these two reaction parameters. Equally, colloidal stabilization was related to reaction temperature and sodium tartrate concentration. It was also determined that Ostwald ripening takes place during sonochemical reaction under our conditions, allowing to understand the mechanism that takes place during synthesis. Gold nanoparticles with main particle size of 17 nm were achieved by this method. Characterization techniques used: Fourier transform infrared spectra (Ftir), X-ray diffraction and Atomic Force Microscope was used in order to determine particle size of the synthetic product of reaction M10c by tapping mode. (Author)

  20. Monomer adsorption of indocyanine green to gold nanoparticles

    NARCIS (Netherlands)

    Guerrini, Luca; Hartsuiker, Liesbeth; Manohar, Srirang; Otto, Cees

    2011-01-01

    NIR-dye encoded gold nanoparticles (GNP) are rapidly emerging as contrast agents in many bio-imaging/sensing applications. The coding process is usually carried out without control or a clear understanding of the metal–liquid interface properties which, in contrast, are critical in determining the t

  1. Oligothia dendrimers for the formation of gold nanoparticles

    NARCIS (Netherlands)

    d'Aleo, A.; Williams, R.M.; Osswald, F.; Edamana, P.; Hahn, U.; van Heyst, J.; Tichelaar, F.D.; Voegtle, F.; De Cola, L.

    2004-01-01

    The synthesis and characterization of oligothia dendrimers and their use for the formation of gold nanoparticles is described. The role played by these dendrimers in controlling the stability and size of the particles is discussed. It is shown that the generation of the dendrimers, as well as the

  2. Ligand adsorption and exchange on pegylated gold nanoparticles

    Science.gov (United States)

    Previous researchers proposed that thiolated poly(ethylene glycol) (PEG-SH) adopts a “mushroom-like” conformation on gold nanoparticles (AuNPs) in water. However, information regarding the size and permeability of the PEG-SH mushroom caps and surface area passivated by the PEG-SH mushroom stems are ...

  3. Design and Fabrication of Microfiber Containing Gold Nanoparticles

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Wang, Guanghui; Hu, Dora Juan Juan

    2010-01-01

    We present a simple fabrication method for embedding gold nanoparticles (GNPs) in a microfiber with two main advantages. The GNPs are positioned within the microfiber securing maximum enhancement of the electrical field and protection of the GNPs from the surroundings; moreover incoupling losses...

  4. Light-Driven Rotary Molecular Motors on Gold Nanoparticles

    NARCIS (Netherlands)

    Pollard, Michael M.; ter Wiel, Matthijs K. J.; van Delden, Richard A.; Vicario, Javier; Koumura, Nagatoshi; van den Brom, Coenraad R.; Meetsma, Auke; Feringa, Ben L.

    2008-01-01

    We report the synthesis of unidirectional light-driven rotary molecular motors based oil chiral overcrowded alkenes and their immobilisation on the surface of gold nanoparticles through two anchors. Using a combination of (1)H and (13)C NMR, UV/Vis and CD spectroscopy, we show that these motors pres

  5. Multiple strategies to activate gold nanoparticles as antibiotics

    Science.gov (United States)

    Zhao, Yuyun; Jiang, Xingyu

    2013-08-01

    Widespread antibiotic resistance calls for new strategies. Nanotechnology provides a chance to overcome antibiotic resistance by multiple antibiotic mechanisms. This paper reviews the progress in activating gold nanoparticles with nonantibiotic or antibiotic molecules to combat bacterial resistance, analyzes the gap between experimental achievements and real clinical application, and suggests some potential directions in developing antibacterial nanodrugs.

  6. Gold Nanoparticles: Recent Advances in the Biomedical Applications.

    Science.gov (United States)

    Zhang, Xiaoying

    2015-07-01

    Among the multiple branches of nanotechnology applications in the area of medicine and biology, Nanoparticle technology is the fastest growing and shows significant future promise. Nanoscale structures, with size similar to many biological molecules, show different physical and chemical properties compared to either small molecules or bulk materials, find many applications in the fields of biomedical imaging and therapy. Gold nanoparticles (AuNPs) are relatively inert in biological environment, and have a number of physical properties that are suitable for several biomedical applications. For example, AuNPs have been successfully employed in inducing localized hyperthermia for the destruction of tumors or radiotherapy for cancer, photodynamic therapy, computed tomography imaging, as drug carriers to tumors, bio-labeling through single particle detection by electron microscopy and in photothermal microscopy. Recent advances in synthetic chemistry makes it possible to make gold nanoparticles with precise control over physicochemical and optical properties that are desired for specific clinical or biological applications. Because of the availability of several methods for easy modification of the surface of gold nanoparticles for attaching a ligand, drug or other targeting molecules, AuNPs are useful in a wide variety of applications. Even though gold is biologically inert and thus shows much less toxicity, the relatively low rate of clearance from circulation and tissues can lead to health problems and therefore, specific targeting of diseased cells and tissues must be achieved before AuNPs find their application for routine human use.

  7. Polymer protected gold nanoparticles: synthesis, characterization and application in catalysis

    OpenAIRE

    Baygazieva, E. K.; Yesmurzayeva, N. N.; Tatykhanova, G. S.; Mun, G. A.; Khutoryanskiy, V. V.; Kudaibergenov, S. E.

    2014-01-01

    This review discusses the stabilization of gold nanoparticles (AuNPs) by nonionic, anionic, cationic and amphoteric polymers. The protocols used for synthesis of AuNPs in aqueous and organic solvents are described. Size, shape and morphology of AuNPs are characterized by various physicochemical methods. Application aspects of polymer-protected AuNPs in catalysis are outlined.

  8. Oligothia dendrimers for the formation of gold nanoparticles

    NARCIS (Netherlands)

    d'Aleo, A.; Williams, R.M.; Osswald, F.; Edamana, P.; Hahn, U.; van Heyst, J.; Tichelaar, F.D.; Voegtle, F.; De Cola, L.

    2004-01-01

    The synthesis and characterization of oligothia dendrimers and their use for the formation of gold nanoparticles is described. The role played by these dendrimers in controlling the stability and size of the particles is discussed. It is shown that the generation of the dendrimers, as well as the po

  9. The epoxidation of propene over gold nanoparticle catalysts

    NARCIS (Netherlands)

    Nijhuis, T.A.; Sacaliuc, E.; Weckhuysen, B.M.

    2008-01-01

    Different gold nanoparticle catalysts on titania, silica, and titanosilicate supports are compared in the hydro-epoxidation of propene. All catalysts tested were active in the propene epoxidation, with Au/TiO2 showing the highest activity at low temperature, but also a high rate of deactivation. It

  10. Aquatic Fern (Azolla Sp.) Assisted Synthesis of Gold Nanoparticles

    Science.gov (United States)

    Jha, Anal K.; Prasad, K.

    2016-02-01

    Aquatic pteridophyte (Azolla sp.) was taken to assess its potential to synthesize the metal (Au) nanoparticles. The synthesized particles were characterized using X-ray, UV-visible, scanning and transmission electron microscopy analyses. Nanoparticles almost spherical in shape having the sizes of 5-17nm are found. UV-visible study revealed the surface plasmon resonance at 538nm. Responsible phytochemicals for the transformation were principally phenolics, tannins, anthraquinone glycosides and sugars present abundantly in the plant thereby bestowing it adaptive prodigality. Also, the use of Azolla sp. for the synthesis of gold nanoparticles offers the benefit of eco-friendliness.

  11. Plant Extract (Bupleurum falcatum) as a Green Factory for Biofabrication of Gold Nanoparticles.

    Science.gov (United States)

    Lee, You Jeong; Cha, Song-Hyun; Lee, Kyoung Jin; Kim, Yeong Shik; Cho, Seonho; Park, Youmie

    2015-09-01

    This work describes a biofabrication process for gold nanoparticles in which the plant extract (Bupleurum falcatum) is used as a reducing agent to convert gold ions to gold nanoparticles. Biofabricated gold nanoparticles with spherical shapes were observed with an average diameter of 10.5 ± 2.3 nm. The color of the gold nanoparticles was purple, with a surface plasmon resonance peak at 542 nm. The face-centered cubic structure of crystalline gold was confirmed by high-resolution X-ray diffraction patterns. The biofabricated gold nanoparticles demonstrated excellent catalytic activity towards the 4-nitrophenol reduction reaction. The current report suggests that plant extracts are valuable natural sources for the biofabrication of gold nanoparticles with excellent catalytic activities.

  12. Shaping and patterning gold nanoparticles via micelle templated photochemistry

    Science.gov (United States)

    Kundrat, F.; Baffou, G.; Polleux, J.

    2015-09-01

    Shaping and positioning noble metal nanostructures are essential processes that still require laborious and sophisticated techniques to fabricate functional plasmonic interfaces. The present study reports a simple photochemical approach compatible with micellar nanolithography and photolithography that enables the growth, arrangement and shaping of gold nanoparticles with tuneable plasmonic resonances on glass substrates. Ultraviolet illumination of surfaces coated with gold-loaded micelles leads to the formation of gold nanoparticles with micro/nanometric spatial resolution without requiring any photosensitizers or photoresists. Depending on the extra-micellar chemical environment and the illumination wavelength, block copolymer micelles act as reactive and light-responsive templates, which enable to grow gold deformed nanoparticles (potatoids) and nanorings. Optical characterization reveals that arrays of individual potatoids and rings feature a localized plasmon resonance around 600 and 800 nm, respectively, enhanced photothermal properties and high temperature sustainability, making them ideal platforms for future developments in nanochemistry and biomolecular manipulation controlled by near-infrared-induced heat.Shaping and positioning noble metal nanostructures are essential processes that still require laborious and sophisticated techniques to fabricate functional plasmonic interfaces. The present study reports a simple photochemical approach compatible with micellar nanolithography and photolithography that enables the growth, arrangement and shaping of gold nanoparticles with tuneable plasmonic resonances on glass substrates. Ultraviolet illumination of surfaces coated with gold-loaded micelles leads to the formation of gold nanoparticles with micro/nanometric spatial resolution without requiring any photosensitizers or photoresists. Depending on the extra-micellar chemical environment and the illumination wavelength, block copolymer micelles act as

  13. Tea-bag-like polymer nanoreactors filled with gold nanoparticles.

    Science.gov (United States)

    Mitschang, Fabian; Schmalz, Holger; Agarwal, Seema; Greiner, Andreas

    2014-05-05

    Gold-containing polymer nanotubes, which showed both catalytic activity and resistance to leaching, were prepared by the "tubes by fiber templates" (TUFT) process. For this purpose, electrospun polymer nonwovens with incorporated poly(L-lactide)-stabilized gold nanoparticles were coated with poly(p-xylylene) by the chemical vapor deposition process, and then the inner fiber templates were removed. The resulting polymer tubes carried encapsulated gold nanoparticles which were shown to be immobilized and featured pronounced catalytic activity towards the hydrolytic oxidation of dimethylphenylsilane and the alcoholysis of dimethylphenylsilane with n-butanol. The macroscopic nonwovens could be used as tea-bag-like catalyst systems and showed excellent reusability. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Gold nanoparticles - the theranostic challenge for PPPM: nanocardiology application.

    Science.gov (United States)

    Spivak, Mykola Ya; Bubnov, Rostyslav V; Yemets, Ilya M; Lazarenko, Liudmyla M; Tymoshok, Natalia O; Ulberg, Zoia R

    2013-06-24

    The article overviews the potential biomedical applications of nanoscale gold particles for predictive, preventive and personalised nanomedicine in cardiology. The review demonstrates the wide opportunities for gold nanoparticles due to their unique biological properties. The use of gold nanoparticles in cardiology is promising to develop fundamentally new methods of diagnosis and treatment. The nanotheranostics in cardiovascular diseases allows the non-invasive imaging associated with simultaneous therapeutic intervention and predicting treatment outcomes. Imaging may reflect the effectiveness of treatment and has become a fundamental optimisation setting for therapeutic protocol. Combining the application of biomolecular and cellular therapies with nanotechnologies foresees the development of complex integrated nanodevices. Nanocardiology may challenge existing healthcare system and economic benefits as cardiovascular diseases are the leading cause of morbidity and mortality at present.

  15. Synthesis of core-shell gold coated magnetic nanoparticles and their interaction with thiolated DNA.

    Science.gov (United States)

    Robinson, Ian; Tung, Le D; Maenosono, Shinya; Wälti, Christoph; Thanh, Nguyen T K

    2010-12-01

    Core-shell magnetic nanoparticles have received significant attention recently and are actively investigated owing to their large potential for a variety of applications. Here, the synthesis and characterization of bimetallic nanoparticles containing a magnetic core and a gold shell are discussed. The gold shell facilitates, for example, the conjugation of thiolated biological molecules to the surface of the nanoparticles. The composite nanoparticles were produced by the reduction of a gold salt on the surface of pre-formed cobalt or magnetite nanoparticles. The synthesized nanoparticles were characterized using ultraviolet-visible absorption spectroscopy, transmission electron microscopy, energy dispersion X-ray spectroscopy, X-ray diffraction and super-conducting quantum interference device magnetometry. The spectrographic data revealed the simultaneous presence of cobalt and gold in 5.6±0.8 nm alloy nanoparticles, and demonstrated the presence of distinct magnetite and gold phases in 9.2±1.3 nm core-shell magnetic nanoparticles. The cobalt-gold nanoparticles were of similar size to the cobalt seed, while the magnetite-gold nanoparticles were significantly larger than the magnetic seeds, indicating that different processes are responsible for the addition of the gold shell. The effect on the magnetic properties by adding a layer of gold to the cobalt and magnetite nanoparticles was studied. The functionalization of the magnetic nanoparticles is demonstrated through the conjugation of thiolated DNA to the gold shell.

  16. Can small hydrophobic gold nanoparticles inhibit β2-microglobulin fibrillation?

    Science.gov (United States)

    Brancolini, Giorgia; Toroz, Dimitrios; Corni, Stefano

    2014-06-01

    Inorganic nanoparticles stabilized by a shell of organic ligands can enhance or suppress the natural propensity of proteins to form fibrils. Functionalization facilitates targeted delivery of the nanoparticles to various cell types, bioimaging, drug delivery and other therapeutic and diagnostic applications. In this study, we provide a computational model of the effect of a prototypical thiol-protected gold nanoparticle, Au25L18- (L = S(CH2)2Ph) on the β2-microglobulin natural fibrillation propensity. To reveal the molecular basis of the protein-nanoparticle association process, we performed various simulations at multiple levels (Classical Molecular Dynamics and Brownian Dynamics) that cover multiple length- and timescales. The results provide a model of the ensemble of structures constituting the protein-gold nanoparticle complexes, and insights into the driving forces for the binding of β2-microglobulin to hydrophobic small size gold nanoparticles. We have found that the small nanoparticles can bind the protein to form persistent complexes. This binding of nanoparticles is able to block the active sites of domains from binding to another protein, thus leading to potential inhibition of the fibrillation activity. A comparison with the binding patches identified for the interaction of the protein with a known inhibitor of fibrillation, supports our conclusion.Inorganic nanoparticles stabilized by a shell of organic ligands can enhance or suppress the natural propensity of proteins to form fibrils. Functionalization facilitates targeted delivery of the nanoparticles to various cell types, bioimaging, drug delivery and other therapeutic and diagnostic applications. In this study, we provide a computational model of the effect of a prototypical thiol-protected gold nanoparticle, Au25L18- (L = S(CH2)2Ph) on the β2-microglobulin natural fibrillation propensity. To reveal the molecular basis of the protein-nanoparticle association process, we performed various

  17. Computational and experimental evaluation of selective substitution of thiolated coumarin derivatives on gold nanoparticles: Surface enhancing Raman scattering and electrochemical studies

    Science.gov (United States)

    Mlambo, Mbuso; Harris, Richard A.; Mashazi, Philani; Sabela, Myalowenkosi; Kanchi, Suvardhan; Madikizela, Lawrence M.; Shumbula, Prince N.; Moloto, Nosipho; Hlatshwayo, Thulani T.; Mdluli, Phumlani S.

    2017-02-01

    Gold nanoparticles (AuNPs) of various sizes were prepared and treated with a mixture of HS-(CH2)11-NHCO-coumarin (act as Raman reporter) and HS-PEG-(CH2)11COOH (as co-stabilizer and also to attach biomarkers on activated sbnd COOH) to produce mixed monolayer protected clusters of gold (AuMMPCs). In this paper, we demonstrate the significance of the HS-(CH2)11-NHCO-coumarin concentration (percentage ratio) on the enhancement factor (EF), and the geometry of the adsorbed ligands on AuNPs of different sizes. The calculated EFs from Raman spectra reveal a significant decrease with an increase in AuNPs sizes. Molecular dynamics calculations were carried out to obtain the adsorption energies for different ratios of HS-PEG-(CH2)11COOH to HS-(CH2)11-NHCO-coumarin. It was found that molecules that adsorb strongly on the surface of the metal, underwent changes in their polarizability and consequently enhanced Raman intensities were observed, and this was in agreement with experimental data.

  18. Preparation of DPPE-Stabilized Gold Nanoparticles

    Science.gov (United States)

    Dungey, Keenan E.; Muller, David P.; Gunter, Tammy

    2005-01-01

    An experiment is presented that introduces students to nanotechnology through the preparation of nanoparticles and their visualization using transmission electron microscopy (TEM). The experiment familiarizes the students with nonaqueous solvents, biphasic reactions, phase-transfer agents, ligands to stabilize growing nanoparticles, and bidentate…

  19. Defining rules for the shape evolution of gold nanoparticles.

    Science.gov (United States)

    Langille, Mark R; Personick, Michelle L; Zhang, Jian; Mirkin, Chad A

    2012-09-05

    The roles of silver ions and halides (chloride, bromide, and iodide) in the seed-mediated synthesis of gold nanostructures have been investigated, and their influence on the growth of 10 classes of nanoparticles that differ in shape has been determined. We systematically studied the effects that each chemical component has on the particle shape, on the rate of particle formation, and on the chemical composition of the particle surface. We demonstrate that halides can be used to (1) adjust the reduction potential of the gold ion species in solution and (2) passivate the gold nanoparticle surface, both of which control the reaction kinetics and thus enable the selective synthesis of a series of different particle shapes. We also show that silver ions can be used as an underpotential deposition agent to access a different set of particle shapes by controlling growth of the resulting gold nanoparticles through surface passivation (more so than kinetic effects). Importantly, we show that the density of silver coverage can be controlled by the amount and type of halide present in solution. This behavior arises from the decreasing stability of the underpotentially deposited silver layer in the presence of larger halides due to the relative strengths of the Ag(+)/Ag(0)-halide and Au(+)/Au(0)-halide interactions, as well as the passivation effects of the halides on the gold particle surface. We summarize this work by proposing a set of design considerations for controlling the growth and final shape of gold nanoparticles prepared by seed-mediated syntheses through the judicious use of halides and silver ions.

  20. CHITOSAN-GOLD NANOPARTICLES AS DELIVERY SYSTEMS FOR CURCUMIN

    Directory of Open Access Journals (Sweden)

    K. Satish Kumar* D. Gnanaprakash, K. Mayilvaganan, C. Arunraj and S. Mohankumar

    2012-11-01

    Full Text Available The present study deals with investigating the effect of chitosan nano particles as carriers for an anticancer drug curcumin. The chitosan-curcumin nanocapsules were prepared in the presence and absence of gold nanoparticles via solvent evaporation method. Scanning electron microscopy and transmission electron microscopy was done to characterize the drug entrapped nanocapsules. The average diameter of gold nanoparticles was found to be in the range of 18-20 nm and size of the nanocapsules was found to be in the range of 200-250 nm. Fourier transform-infrared analysis revealed no possible interactions among the constituents with the chitosan nanoparticles. The controlled drug release of anticancer drug entrapped nanocapsules was carried out in 0.1M HCl and 0.1M phosphate buffer (pH 7. Experimental studies revealed that curcumin encapsulated chitosan with gold nanoparticles was controlled and steady when compared with curcumin encapsulated chitosan nanoparticles. Application of in vitro drug release date to various kinetic equations indicated higuchi matrix model indicating uniform distribution of curcumin in the nanocapsules.

  1. Aggregation behaviour of gold nanoparticles in presence of chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Collado-González, Mar; Fernández Espín, Vanesa [University of Murcia, Department of Physical Chemistry (Spain); Montalbán, Mercedes G. [University of Murcia, Department of Chemical Engineering (Spain); Pamies, Ramón [Technical University of Cartagena, Department of Material Engineering and Manufacturing (Spain); Hernández Cifre, José Ginés; Díaz Baños, F. Guillermo, E-mail: fgb@um.es [University of Murcia, Department of Physical Chemistry (Spain); Víllora, Gloria [University of Murcia, Department of Chemical Engineering (Spain); García de la Torre, José [University of Murcia, Department of Physical Chemistry (Spain)

    2015-06-15

    Chitosan (CS) is a biocompatible polysaccharide with positive charge that is widely used as a coating agent for negatively charged nanoparticles. However, the types of structures that emerge by combining CS and nanoparticles as well as their behaviour are still poorly understood. In this work, we characterize the nanocomposites formed by gold nanoparticles (AuNPs) and CS and study the influence of CS in the expected aggregation process that should experience those nanoparticles under the favourable conditions of low pH and high ionic strength. Thus, at the working CS concentration, we observe the existence of CS structures that quickly trap the AuNPs and avoid the formation of nanoparticle aggregates in environmental conditions that, otherwise, would lead to such an aggregation.

  2. Aggregation behaviour of gold nanoparticles in presence of chitosan

    Science.gov (United States)

    Collado-González, Mar; Fernández Espín, Vanesa; Montalbán, Mercedes G.; Pamies, Ramón; Hernández Cifre, José Ginés; Díaz Baños, F. Guillermo; Víllora, Gloria; García de la Torre, José

    2015-06-01

    Chitosan (CS) is a biocompatible polysaccharide with positive charge that is widely used as a coating agent for negatively charged nanoparticles. However, the types of structures that emerge by combining CS and nanoparticles as well as their behaviour are still poorly understood. In this work, we characterize the nanocomposites formed by gold nanoparticles (AuNPs) and CS and study the influence of CS in the expected aggregation process that should experience those nanoparticles under the favourable conditions of low pH and high ionic strength. Thus, at the working CS concentration, we observe the existence of CS structures that quickly trap the AuNPs and avoid the formation of nanoparticle aggregates in environmental conditions that, otherwise, would lead to such an aggregation.

  3. Optimization and stabilization of gold nanoparticles by using herbal plant extract with microwave heating

    Science.gov (United States)

    Yasmin, Akbar; Ramesh, Kumaraswamy; Rajeshkumar, Shanmugam

    2014-04-01

    In this study, we have synthesized the gold nanoparticles by using Hibiscus rosa-sinensis, a medicinal plant. The gold nanoparticles were synthesized rapidly by the involvement of microwave heating. By changing of plant extract concentration, gold solution concentration, microwave heating time and power of microwave heating the optimized condition was identified. The surface Plasmon resonance found at 520 nm confirmed the gold nanoparticles synthesis. The spherical sized nanoparticles in the size range of 16-30 nm were confirmed by Transmission Electron Microscope (TEM). The stability of the nanoparticles is very well proved in the invitro stability tests. The biochemical like alkaloids and flavonoids play a vital role in the nanoparticles synthesis was identified using the Fourier Transform Infrared Spectroscopy (FTIR). Combining the phytochemical and microwave heating, the rapid synthesis of gold nanoparticles is the novel process for the medically applicable gold nanoparticles production.

  4. Intrinsic effects of gold nanoparticles on proliferation and invasion activity in SGC-7901 cells.

    Science.gov (United States)

    Wu, Yucheng; Zhang, Qingqing; Ruan, Zhongbao; Yin, Yigang

    2016-03-01

    Although biomedical applications of functionalized nanoparticles have taken significant strides, biological characterization of unmodified nanoparticles remains unclear. In the present study, we investigated the cell viability and invasion activity of gastric cancer cells after treatment with gold nanoparticles. The growth of SGC-7901 cells was inhibited significantly after treatment with 5-nm gold nanoparticles, and the cell invasion decreased markedly. These effects were not seen by different size gold nanoparticles (10, 20 and 40 nm). The attenuated invasion activity may be associated with the decreased expression of matrix metalloproteinase 9 and intercellular adhesion molecule-1. These data indicated that the response of SGC-7901 cells to gold nanoparticles was strongly associated with their unique size-dependent physiochemical properties. Therefore, we provided new evidence for the effect of gold nanoparticles on gastric cancer cell proliferation and invasion in vitro, making a contribution to the application of gold nanoparticles to novel therapies in gastric cancer.

  5. Modification of Gold Surface with Gold Nanoparticles and Cyclohexyl Dithiocarbamate as a Selective Sensor for Cysteine

    Directory of Open Access Journals (Sweden)

    Ehab AlShamaileh

    2013-01-01

    Full Text Available The self-assembly of cyclohexylamine dithiocarbamate (C6DTC on gold (Au and gold nanoparticles (AuNPs was studied electrochemically using cyclic voltammetry (CV. Cyclic voltammetry was used to study the system Fe(CN63-/Fe(CN64- at the electrode surface of (C6DTC/Au and (C6DTC/AuNPs. The application of the resulting chemically modified surface as a selective sensor for cysteine, among other amino acids, was investigated. Linear oxidative desorption technique was used to characterize the modified electrode that consists of the self-assembled monolayer of cyclohexylamine dithiocarbamate on gold nanoparticles deposited on Au electrode (C6DTC/AuNPs/Au. The results showed an enhancement in the oxidation peak of cysteine on the modified electrode and hence a greater sensitivity.

  6. Not all that glitters is gold - Electron microscopy study on uptake of gold nanoparticles in Daphnia magna and related artefacts

    DEFF Research Database (Denmark)

    Jensen, Louise Helene Søgaard; Skjolding, Lars Michael; Thit, Amalie

    2016-01-01

    techniques are used to investigate internalization of 10 nm gold nanoparticles in Daphnia magna gut lumen and gut epithelial cells upon 24h exposure and outline potential artefacts, i.e. high contract precipitates from sample preparation related to these techniques. Light sheet microscopy confirmed...... accumulation of gold nanoparticles in the gut lumen. Scanning transmission electron microscopy and elemental analysis revealed gold nanoparticles attached to the microvilli of gut cells. Interestingly, the peritrophic membrane appeared to act as a semipermeable barrier between the lumen and the gut epithelium......, permitting only single particles through. Structures resembling nanoparticles were also observed inside gut cells. As elemental analysis could not verify these to be gold they were likely artifacts from the preparation, such as osmium and iron. Importantly, gold nanoparticles were in fact found inside...

  7. Luminescent Gold Nanoparticles with Mixed Valence States Generated from Dissociation of Polymeric Au (I) Thiolates

    OpenAIRE

    Zhou, Chen; Sun, Ce; Yu, Mengxiao; Qin, Yanping; Wang, Jinguo; Kim, Moon; Zheng, Jie

    2010-01-01

    Dissociation process of glutathione-gold(I) polymers in aqueous solution resulted in the formation of a class of ~2 nm gold nanoparticles. Different from the same sized but NaBH4 reduced gold nanoparticles, these nanoparticles exhibit strong luminescence but no surface plasmon absorption. Luminescence lifetimes of the nanoparticles were found strongly dependent on excitation wavelengths, and singlet and triplet excited states involving the emission were found degenerate in energy. X-ray photo...

  8. Facile Synthesis of Gold-nanoparticles-decorated Polymer Assemblies and Core-Shell Gold Nanoparticles Using Pluronic Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    SHOU Qing-hui; GUO Chen; GAO Hong-shuai; ZHOU Hua-cong; LIU Chun-zhao; LIU Hui-zhou

    2011-01-01

    Abstract:Synthesis of gold nanoparticles (AuNPs) and Pluronic triblock copolymer composite in aqueous medium was studied.Gold-polymer nanocomposite with different structures was fabricated by tailoring the molar ratio of gold precursors to Pluronic P123 molecules or pH value of the P123 solution.When a lower volume ratio of [AuCl4-]/[P123] (0.05) was employed at pH 11.1,a nanostructure similar to plum pudding was obtained.AuNPs with an average diameter of 13.1 nm were embedded in Pluronic assemblies,and each one held about 21 single gold nanoparticles.When [AuCl4-]/[P123] was increased to 0.1,core-shell structure was obtained if the pH value was in the range of 10.6~11.6,while gold polyhedra were fabricated when pH value was 8.1.Typical core-shell AuNPs had an average diameter of 9.6 nm with a narrow size distribution,while gold polyhedras with a mean diameter of 12.8 nm was obtained.The specific morphologies of the resultant nanocomposite were presumably obtained due to the synergistic interaction among the reactants.

  9. Enhancing nanoparticle electrodynamics with gold nanoplate mirrors.

    Science.gov (United States)

    Yan, Zijie; Bao, Ying; Manna, Uttam; Shah, Raman A; Scherer, Norbert F

    2014-05-14

    Mirrors and optical cavities can modify and enhance matter-radiation interactions. Here we report that chemically synthesized Au nanoplates can serve as micrometer-size mirrors that enhance electrodynamic interactions. Because of their plasmonic properties, the Au nanoplates enhance the brightness of scattered light from Ag nanoparticles near the nanoplate surface in dark-field microscopy. More importantly, enhanced optical trapping and optical binding of Ag nanoparticles are demonstrated in interferometric optical traps created from a single laser beam and its reflection from individual Au nanoplates. The enhancement of the interparticle force constant is ≈20-fold more than expected from the increased intensity due to standing wave interference. We show that the additional stability for optical binding arises from the restricted axial thermal motion of the nanoparticles that couples to and reduces the fluctuations in the lateral plane. This new mechanism greatly advances the photonic synthesis of ultrastable nanoparticle arrays and investigation of their properties.

  10. Liquid crystals from mesogens containing gold nanoparticles

    Science.gov (United States)

    Lewandowski, Wiktor; Gorecka, Ewa

    Long-range ordered structures made of nanoparticles are perspective materials for future optical, electronic and sensing technologies. Conspicuous physicochemical features of nanoparticle aggregates originate from distant-dependent collective interactions, therefore lately a lot of attention was put to the development of assembly strategies allowing control over nanoparticle spatial distribution. In this chapter we will focus on the assembly process based on using thermotropic liquid-crystalline molecules as surface nanoparticle ligands. First, we discuss architectural parameters that inuence structure and thermal properties of the aggregates. Then, we show that this approach enables formation of assemblies with metamaterial characteristic, gives access to dynamic materials with light-, magneto- and thermo-responsive behavior and allows formation of aggregates with unique structures, which all make this strategy an attractive object of research.

  11. SDS bubbles functionalized with Gold nanoparticles and SERS applications

    Science.gov (United States)

    Navarro-Badilla, A.; Hurtado, R. Britto; Cortez-Valadez, M.; Perez-Rodriguez, A.; Flores-Acosta, M.; Maldonado-Arce, A.

    2017-03-01

    We present a method of incorporation of gold nanoparticles in SDS (sodium dodecyl sulfate) bubbles with a low polydispersity index (monodispersed nanoparticles). Both the bubbles and nanoparticles maintained their structural and morphologic properties after functionalization. The bubbles present a radio of 0.38 mm with a standard deviation of±0.018 mm. The gold nanoparticles were obtained with sucrose as the catalytic agent and ascorbic acid as the reducing agent. The nanoparticles display several geometric morphologies as well as sizes inferior to 50 nm, as observed in the images obtained with Transmission Electron Microscopy (TEM). The optical properties were studied by optical absorption spectroscopy. The absorption band linked to the surface plasmon resonance (SPR) is located at 550 nm before and after the functionalization of the bubbles. Moreover, microscopic bubbles with a diameter smaller than 1 μm with the ability to stabilize nanoparticles in their surface were found in isolated regions of the sample. Additionally, the Surface Enhancement Raman Spectroscopy (SERS) properties of the colloid were analyzed with common drugs.

  12. The optical nonlinearity of gold nanoparticles prepared by bioreduction method

    Science.gov (United States)

    Balbuena Ortega, A.; Arroyo Carrasco, M. L.; Gayou, V. L.; Orduña Díaz, A.; Delgado Macuil, R.; Rojas López, Marlon

    2013-11-01

    Nonlinear optical and electronic properties of nanosized metal particles have drawn considerable attention because of their strong and size-dependent plasmon resonance absorption. In a metal nanoparticle system such as gold dispersed in a transparent matrix, an absorption peak due to surface plasmon resonance is usually observed in the visible spectral region. Metal nanoparticles are of special interest as nonlinear materials for optical switching and computing because of their relatively large third-order nonlinearity (χ3) and ultrafast response time. The purpose of this study was to analyze the nonlinear optical properties of biosynthesized gold nanoparticles. The samples were prepared by biosynthesis method using yeast extract as reducing agent and the nonlinear optical properties of the nanoparticles were investigated using a single beam Z-scan technique with a beam power of 20 mW and operated at wavelength of 514 nm. The reaction between metal ions and yeast extracts were monitored by UV-visible spectra of Au nanoparticles in aqueous solution with different pH (3-6). The surface plasmon peak position was shifted from 528 nm to 573 nm, according to of pH variation 4 to 6. The average particle size was calculated by the absorption peak position using the Fernig method, from 42 to 103 nm. The z-scan curves showed a negative nonlocal nonlinear refractive index with a magnitude dependent on the nanoparticle size.

  13. Neural network potentials for dynamics and thermodynamics of gold nanoparticles

    Science.gov (United States)

    Chiriki, Siva; Jindal, Shweta; Bulusu, Satya S.

    2017-02-01

    For understanding the dynamical and thermodynamical properties of metal nanoparticles, one has to go beyond static and structural predictions of a nanoparticle. Accurate description of dynamical properties may be computationally intensive depending on the size of nanoparticle. Herein, we demonstrate the use of atomistic neural network potentials, obtained by fitting quantum mechanical data, for extensive molecular dynamics simulations of gold nanoparticles. The fitted potential was tested by performing global optimizations of size selected gold nanoparticles (Aun, 17 ≤ n ≤ 58). We performed molecular dynamics simulations in canonical (NVT) and microcanonical (NVE) ensembles on Au17, Au34, Au58 for a total simulation time of around 3 ns for each nanoparticle. Our study based on both NVT and NVE ensembles indicate that there is a dynamical coexistence of solid-like and liquid-like phases near melting transition. We estimate the probability at finite temperatures for set of isomers lying below 0.5 eV from the global minimum structure. In the case of Au17 and Au58, the properties can be estimated using global minimum structure at room temperature, while for Au34, global minimum structure is not a dominant structure even at low temperatures.

  14. Gold and silver nanoparticles from Trianthema decandra: synthesis, characterization, and antimicrobial properties

    Science.gov (United States)

    Geethalakshmi, R; Sarada, DVL

    2012-01-01

    Background There is an increasing commercial demand for nanoparticles due to their wide applicability in various markets, including medicine, catalysis, electronics, chemistry, and energy. In this report, a simple and ecofriendly chemical reaction for the synthesis of gold and silver nanoparticles from Trianthema decandra (Aizoaceae) has been developed. Methods and results On treatment of aqueous solutions containing chloroauric acid or silver nitrate with root extract of T. decandra, stable gold or silver nanoparticles were rapidly formed. The kinetics of reduction of gold and silver ions during the reaction was analyzed by ultraviolet-visible spectroscopy. Field emission-scanning electron microscopy showed formation of gold nanoparticles in various shapes, including spherical, cubical, triangular, and hexagonal, while silver nanoparticles were spherical. The size of the gold nanoparticles was 33–65 nm and that of the silver nanoparticles was 36–74 nm. Energy dispersive x-ray and Fourier transform infrared spectroscopy confirmed the presence of metallic gold and metallic silver in the respective nanoparticles. The antimicrobial properties of the synthesized nanoparticles were analyzed using the Kirby-Bauer method. The results show varied susceptibility of microorganisms to the gold and silver nanoparticles. Conclusion It is believed that phytochemicals present in T. decandra extract reduce the silver and gold ions into metallic nanoparticles. This strategy reduces the cost of production and the environmental impact. The silver and gold nanoparticles formed showed strong activity against all microorganisms tested. PMID:23091381

  15. Gold Nanoparticles as the Catalyst of Single-Walled Carbon Nanotube Synthesis

    Directory of Open Access Journals (Sweden)

    Yoshikazu Homma

    2014-03-01

    Full Text Available Gold nanoparticles have been proven to act as efficient catalysts for chemical reactions, such as oxidation and hydrogen production. In this review we focus on a different aspect of the catalysis of gold nanoparticles; single-walled carbon nanotube (SWCNT synthesis. This is not a traditional meaning of catalytic reaction, but SWCNTs cannot be synthesized without nanoparticles. Previously, gold was considered as unsuitable metal species as the catalyst of SWCNT synthesis. However, gold nanoparticles with diameters smaller than 5 nm were found to effectively produce SWCNTs. We discuss the catalysis of gold and related metals for SWCNT synthesis in comparison with conventional catalysts, such as iron, cobalt, and nickel.

  16. Covalent assembly of gold nanoparticles for nonvolatile memory applications.

    Science.gov (United States)

    Gupta, Raju Kumar; Kusuma, Damar Yoga; Lee, P S; Srinivasan, M P

    2011-12-01

    This work reports a versatile approach for enhancing the stability of nonvolatile memory devices through covalent assembly of functionalized gold nanoparticles. 11-mercapto-1-undecanol functionalized gold nanoparticles (AuNPs) with a narrow size distribution and particle size of about 5 nm were synthesized. Then, the AuNPs were immobilized on a SiO(2) substrate using a functionalized polymer as a surface modifier. Microscopic and spectroscopic techniques were used to characterize the AuNPs and their morphology before and after immobilization. Finally, a metal-insulator-semiconductor (MIS) type memory device with such covalently anchored AuNPs as a charge trapping layer was fabricated. The MIS structure showed well-defined counterclockwise C-V hysteresis curves indicating a good memory effect. The flat band voltage shift was 1.64 V at a swapping voltage between ±7 V. Furthermore, the MIS structure showed a good retention characteristic up to 20,000 s. The present synthetic route to covalently immobilize gold nanoparticles system will be a step towards realization for the nanoparticle-based electronic devices and related applications.

  17. Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro

    Directory of Open Access Journals (Sweden)

    Speshock Janice

    2011-01-01

    Full Text Available Abstract 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.

  18. Information processing schemes based on monolayer protected metallic nanoclusters.

    Science.gov (United States)

    Cervera, Javier; Mafé, Salvador

    2011-09-01

    Nanostructures are potentially useful as building blocks to complement future electronics because of their high versatility and packing densities. The fabrication and characterization of particular nanostructures and the use of new theoretical tools to describe their properties are receiving much attention. However, the integration of these individual systems into general schemes that could perform simple tasks is also necessary because modern electronics operation relies on the concerted action of many basic units. We review here new conceptual schemes that can allow information processing with ligand or monolayer protected metallic nanoclusters (MPCs) on the basis of the experimentally demonstrated and theoretically described electrical characteristics of these nanostructures. In particular, we make use of the tunnelling current through a metallic nanocluster attached to the electrodes by ligands. The nanostructure is described as a single electron transistor (SET) that can be gated by an external potential. This fact permits exploiting information processing schemes in approximately defined arrays of MPCs. These schemes include: (i) binary, multivalued, and reversible logic gates; (ii) an associative memory and a synchronization circuit; and (iii) two signal processing nanodevices based on parallel arrays of MPCs and nanoswitches. In each case, the practical operation of the nanodevice is based on the SET properties of MPCs reported experimentally. We examine also some of the practical problems that should be addressed in future experimental realizations: the stochastic nature of the electron tunnelling, the relatively low operation temperatures, and the limited reliability caused by the weak signals involved and the nanostructure variability. The perspectives to solve these problems are based on the potentially high degree of scalability of the nanostructures.

  19. Functionalization and Characterization of Gold Nanoparticles

    Science.gov (United States)

    Techane, Sirnegeda D.

    2011-12-01

    Surface characterization of gold nanoparticles (AuNPs) is necessary to obtain a thorough understanding of the AuNP properties and ultimately realize their full potential in applications. The work described in this dissertation strives to the structure and composition of AuNPs using highly surface sensitive techniques such as X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) in addition to the more widely used characterization techniques such as transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR) and UV-VIS spectroscopy. Self-assembled monolayers (SAMs) of alkanethiols were used to modify AuNPs surfaces to create positively and negatively charged surfaces. Functionalization with carboxylic acid terminated alkanethiol SAMs (COON-SAMs) was first optimized to produce clean and stable negatively charged AuNPs. Using 14nm and 40nm diameter AuNPs in combination with C11 and C16 chain length COOH-SAMs, it was found that addition of NH4OH during functionalization coupled with dialysis purification produced AuNPs that did not aggregate and did not have unbound thiols. Effects of AuNP size and COOH-SAM chain lengths were studied using 14, 25 and 40nm average diameter AuNPs functionalized with C6, C8, C11 and C16 COOH-SAMs. Flat Au surfaces were also functionalized with the COOH-SAMs for comparison. It was shown that the 14nm AuNPs with C16 COOH-SAMs were the most stable and had crystalline-like, well-ordered SAM structures. The SAMs on the 40nm AuNPs had similar surface chemistry as the SAMs on the flat Au surfaces. The effective photoelectron take-off angle of the C16 COOH-SAM decreased when the size of the AuNP increased. It was also shown that when using Kratos AxisUltra DLD XPS instrument in the hybrid mode, it was important to consider effects of both the hybrid mode and the AuNPs curvature when calculating overlayer thickness of the SAMs on AuNPs. Using the Kratos in the electrostatic

  20. Shape and surface effects on the cytotoxicity of nanoparticles: Gold nanospheres versus gold nanostars.

    Science.gov (United States)

    Favi, Pelagie Marlene; Gao, Ming; Johana Sepúlveda Arango, Liuda; Ospina, Sandra Patricia; Morales, Mariana; Pavon, Juan Jose; Webster, Thomas Jay

    2015-11-01

    Gold nanoparticles are materials with unique optical properties that have made them very attractive for numerous biomedical applications. With the increasing discovery of techniques to synthesize novel nanoparticles such as star-shaped gold nanoparticles for biomedical applications, the safety and performance of these new nanomaterials must be systematically assessed before use. In this study, gold nanostars (AuNSTs) with multibranched surface structures were synthesized, and their influence on the cytotoxicity of human skin fibroblasts and rat fat pad endothelial cells (RFPECs) were assessed and compared with that of gold nanospheres (AuNSPs) with unbranched surfaces. Results showed that the AuNSPs with diameters of approximately 61.46 nm showed greater toxicity with fibroblast cells and RFPECs compared with the synthesized AuNSTs with diameters of approximately 33.69 nm. The AuNSPs were lethal at concentrations of 40 μg/mL for both cell lines, whereas the AuNSTs were less toxic at higher concentrations (400 μg/mL). The calculated IC50 (50% inhibitory concentration) values of the AuNSPs exposed to fibroblast cells were greater at 1 and 4 days of culture (26.4 and 27.7 μg/mL, respectively) compared with the RFPECs (13.6 and 13.8 μg/mL, respectively), indicating that the AuNSPs have a greater toxicity to endothelial cells. It was proposed that possible factors that could be promoting the reduced toxicity effects of the AuNSTs to fibroblast cells and RFPECs, compared with the AuNSPs may be size, surface chemistry, and shape of the gold nanoparticles. The reduced cell toxicity observed with the AuNSTs suggests that AuNSTs may be a promising material for use in biomedical applications.

  1. Enhanced chemiluminescence-based detection on gold substrate after electrografting of diazonium precursor-coated gold nanoparticles.

    Science.gov (United States)

    Houmed Adabo, Ali; Zeggari, Rabah; Mohamed Saïd, Nasser; Bazzi, Rana; Elie-Caille, Céline; Marquette, Christophe; Martini, Matteo; Tillement, Olivier; Perriat, Pascal; Chaix, Carole; Boireau, Wilfrid; Roux, Stéphane

    2016-04-01

    Since it was demonstrated that nanostructured surfaces are more efficient for the detection based on the specific capture of analytes, there is a real need to develop strategies for grafting nanoparticles onto flat surfaces. Among the different routes for the functionalization of a surface, the reduction of diazonium salts appears very attractive for the covalent immobilization of nanoparticles because this method does not require a pre-treatment of the surface. For achieving this goal, gold nanoparticles coated by precursor of diazonium salts were synthesized by reduction of gold salt in presence of mercaptoaniline. These mercaptoaniline-coated gold nanoparticles (Au@MA) were successfully immobilized onto various conducting substrates (indium tin oxide (ITO), glassy carbon (GC) and gold electrodes with flat terraces) after addition of sodium nitrite at fixed potential. When applied onto the gold electrodes, such a grafting strategy led to an obvious enhancement of the luminescence of luminol used for the biodetection.

  2. Dielectrophoresis of gold nanoparticles conjugated to DNA origami structures

    Science.gov (United States)

    Wiens, Matthew; Lakatos, Mathias; Heerwig, Andreas; Ostermaier, Frieder; Haufe, Nora

    2016-01-01

    Summary DNA nanostructures are promising construction materials to bridge the gap between self-assembly of functional molecules and conventional top-down fabrication methods in nanotechnology. Their positioning onto specific locations of a microstructured substrate is an important task towards this aim. Here we study manipulation and positioning of pristine and of gold nanoparticle-conjugated tubular DNA origami structures using ac dielectrophoresis. The dielectrophoretic behavior was investigated employing fluorescence microscopy. For the pristine origami, a significant dielectrophoretic response was found to take place in the megahertz range, whereas, due to the higher polarizability of the metallic nanoparticles, the nanoparticle/DNA hybrid structures required a lower electrical field strength and frequency for a comparable trapping at the edges of the electrode structure. The nanoparticle conjugation additionally resulted in a remarkable alteration of the DNA structure arrangement. The growth of linear, chain-like structures in between electrodes at applied frequencies in the megahertz range was observed. The long-range chain formation is caused by a local, gold nanoparticle-induced field concentration along the DNA nanostructures, which in turn, creates dielectrophoretic forces that enable the observed self-alignment of the hybrid structures. PMID:27547612

  3. Dielectrophoresis of gold nanoparticles conjugated to DNA origami structures.

    Science.gov (United States)

    Henning-Knechtel, Anja; Wiens, Matthew; Lakatos, Mathias; Heerwig, Andreas; Ostermaier, Frieder; Haufe, Nora; Mertig, Michael

    2016-01-01

    DNA nanostructures are promising construction materials to bridge the gap between self-assembly of functional molecules and conventional top-down fabrication methods in nanotechnology. Their positioning onto specific locations of a microstructured substrate is an important task towards this aim. Here we study manipulation and positioning of pristine and of gold nanoparticle-conjugated tubular DNA origami structures using ac dielectrophoresis. The dielectrophoretic behavior was investigated employing fluorescence microscopy. For the pristine origami, a significant dielectrophoretic response was found to take place in the megahertz range, whereas, due to the higher polarizability of the metallic nanoparticles, the nanoparticle/DNA hybrid structures required a lower electrical field strength and frequency for a comparable trapping at the edges of the electrode structure. The nanoparticle conjugation additionally resulted in a remarkable alteration of the DNA structure arrangement. The growth of linear, chain-like structures in between electrodes at applied frequencies in the megahertz range was observed. The long-range chain formation is caused by a local, gold nanoparticle-induced field concentration along the DNA nanostructures, which in turn, creates dielectrophoretic forces that enable the observed self-alignment of the hybrid structures.

  4. In vivo integrity of polymer-coated gold nanoparticles

    Science.gov (United States)

    Kreyling, Wolfgang G.; Abdelmonem, Abuelmagd M.; Ali, Zulqurnain; Alves, Frauke; Geiser, Marianne; Haberl, Nadine; Hartmann, Raimo; Hirn, Stephanie; de Aberasturi, Dorleta Jimenez; Kantner, Karsten; Khadem-Saba, Gülnaz; Montenegro, Jose-Maria; Rejman, Joanna; Rojo, Teofilo; de Larramendi, Idoia Ruiz; Ufartes, Roser; Wenk, Alexander; Parak, Wolfgang J.

    2015-07-01

    Inorganic nanoparticles are frequently engineered with an organic surface coating to improve their physicochemical properties, and it is well known that their colloidal properties may change upon internalization by cells. While the stability of such nanoparticles is typically assayed in simple in vitro tests, their stability in a mammalian organism remains unknown. Here, we show that firmly grafted polymer shells around gold nanoparticles may degrade when injected into rats. We synthesized monodisperse radioactively labelled gold nanoparticles (198Au) and engineered an 111In-labelled polymer shell around them. Upon intravenous injection into rats, quantitative biodistribution analyses performed independently for 198Au and 111In showed partial removal of the polymer shell in vivo. While 198Au accumulates mostly in the liver, part of the 111In shows a non-particulate biodistribution similar to intravenous injection of chelated 111In. Further in vitro studies suggest that degradation of the polymer shell is caused by proteolytic enzymes in the liver. Our results show that even nanoparticles with high colloidal stability can change their physicochemical properties in vivo.

  5. Dielectrophoresis of gold nanoparticles conjugated to DNA origami structures

    Directory of Open Access Journals (Sweden)

    Anja Henning-Knechtel

    2016-07-01

    Full Text Available DNA nanostructures are promising construction materials to bridge the gap between self-assembly of functional molecules and conventional top-down fabrication methods in nanotechnology. Their positioning onto specific locations of a microstructured substrate is an important task towards this aim. Here we study manipulation and positioning of pristine and of gold nanoparticle-conjugated tubular DNA origami structures using ac dielectrophoresis. The dielectrophoretic behavior was investigated employing fluorescence microscopy. For the pristine origami, a significant dielectrophoretic response was found to take place in the megahertz range, whereas, due to the higher polarizability of the metallic nanoparticles, the nanoparticle/DNA hybrid structures required a lower electrical field strength and frequency for a comparable trapping at the edges of the electrode structure. The nanoparticle conjugation additionally resulted in a remarkable alteration of the DNA structure arrangement. The growth of linear, chain-like structures in between electrodes at applied frequencies in the megahertz range was observed. The long-range chain formation is caused by a local, gold nanoparticle-induced field concentration along the DNA nanostructures, which in turn, creates dielectrophoretic forces that enable the observed self-alignment of the hybrid structures.

  6. Antibacterial nanocarriers of resveratrol with gold and silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sohyun [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); Cha, Song-Hyun [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, Inyoung [School of Civil, Environmental and Architecture Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 136-701 (Korea, Republic of); Park, Soomin [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Yohan [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); Cho, Seonho [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Youmie, E-mail: youmiep@inje.ac.kr [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

    2016-01-01

    This study focused on the preparation of resveratrol nanocarrier systems and the evaluation of their in vitro antibacterial activities. Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) for resveratrol nanocarrier systems were synthesized using green synthetic routes. During the synthesis steps, resveratrol was utilized as a reducing agent to chemically reduce gold and silver ions to AuNPs and AgNPs. This system provides green and eco-friendly synthesis routes that do not involve additional chemical reducing agents. Resveratrol nanocarriers with AuNPs (Res-AuNPs) and AgNPs (Res-AgNPs) were observed to be spherical and to exhibit characteristic surface plasmon resonance at 547 nm and at 412–417 nm, respectively. The mean size of the nanoparticles ranged from 8.32 to 21.84 nm, as determined by high-resolution transmission electron microscopy. The face-centered cubic structure of the Res-AuNPs was confirmed by high-resolution X-ray diffraction. Fourier-transform infrared spectra indicated that the hydroxyl groups and C=C in the aromatic ring of resveratrol were involved in the reduction reaction. Res-AuNPs retained excellent colloidal stability during ultracentrifugation and re-dispersion, suggesting that resveratrol also played a role as a capping agent. Zeta potentials of Res-AuNPs and Res-AgNPs were in the range of − 20.58 to − 48.54 mV. Generally, against Gram-positive and Gram-negative bacteria, the Res-AuNPs and Res-AgNPs exhibited greater antibacterial activity compared to that of resveratrol alone. Among the tested strains, the highest antibacterial activity of the Res-AuNPs was observed against Streptococcus pneumoniae. The addition of sodium dodecyl sulfate during the synthesis of Res-AgNPs slightly increased their antibacterial activity. These results suggest that the newly developed resveratrol nanocarrier systems with metallic nanoparticles show potential for application as nano-antibacterial agents with enhanced activities. - Highlights

  7. Role of Gold Nanoparticles in Early Detection of Oral Cancer

    Directory of Open Access Journals (Sweden)

    P Sanjay Reddy

    2010-01-01

    Nanotechnology is the science of the small; the very small. It is the use and manipulation of matter at a tiny scale. At this size, atoms and molecules work differently and provide a variety of surprising and interesting uses. These nanoparticles can be used to detect/mondor cancer (by utilizing or adding optical, magnetic, and fluorescent properties. This novel imaging tool can lead to significant improvements in cancer therapy due to earlier detection, accurate staging and microtumor identification. In this review, we will summarize the current state of the art of gold nanoparticles in early detection of oral cancer.

  8. The detection of HBV DNA with gold nanoparticle gene probes

    Institute of Scientific and Technical Information of China (English)

    Dong Xi; Xiaoping Luo; Qin Ning; Qianghua Lu; Kailun Yao; Zuli Liu

    2007-01-01

    Objective:Gold nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Methods:Alkanethiol modified oligonucleotide was bound with self-made Au nanoparticles to form nanoparticle HBV DNA gene probes, through covalent binding of Au-S. By using a fluorescence-based method, the number of thiol-derivatized, single-stranded oligonucleotides and their hybridization efficiency with complementary oligonucleotides in solution was determined. With the aid of Au nanoparticle-supported mercapto-modified oligonucleotides serving as detection probes, and oligonucleotides immobilized on a nylon membrane surface acting as capturing probes,HBV DNA was detected visually by sandwich hybridization based on highly sensitive aggregation and silver staining. The modified nanoparticle HBV DNA gene probes were also used to detect the HBV DNA extracted from serum in patients with hepatitis B. Results:Compared with bare Au nanoparticles, oligonucleotide modified nanoparticles had a higher stability in NaCl solution or under high temperature environment and the absorbance peak of modified Au nanoparticles shifted from 520nm to 524nm. For Au nanoparticles, the maximal oligonucleotide surface coverage of hexaethiol 30-mer oligonucleotide was (132 ± 10) oligonucleotides per nanoparticle, and the percentage of hybridization strands on nanoparticles was (22 ± 3% ). Based on a two-probe sandwich hybridization/nanoparticle amplification/silver staining enhancement method, Au nanoparticle gene probes could detect as low as 10-11 mol/L composite HBV DNA molecules on a nylon membrane and the PCR products of HBV DNA visually. As made evident by transmission electron microscopy, the nanoparticles assembled into large network aggregates when nanoparticle HBV DNA gene probes were applied to detect HBV DNA molecules in liquid. Conclusion:Our results showed that successfully prepared Au nanoparticle HBV DNA gene probes could be used to

  9. Laser-based transfection with conjugated gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Cuiping Yao; Xiaochao Qu; Zhenxi Zhang

    2009-01-01

    The irradiation of cells combined with the immunoconjugate of gold nanoparticles by the short pulse laser can make the plasma membrane be transiently permeabilized,which can be used to transfer exogenous molecules into the cells.We explore this technique as a novel gene transfection method for floating cells.Three different floating cells exposed to the laser are selectively transfected with fluorescein isothiocyanatedextran,antibody,and green fluorescent protein (GFP) coding plasmids,and the viability of cells are determined by propidium iodide.For fluorescein isothiocyanate-dextran,the best transfection efficiency of 65% is obtained;for the antibody,it is 74%;whereas for the green fluorescent protein coding plasmids,a very small transfection efficiency is gained.If the transfection efficiency is improved,gold nanoparticles will be very useful as mediator for gene transfection in living cells.

  10. Apertureless SNOM study on gold nanoparticles: Experiments and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Weizhe; Kimel, Alexey; Kirilyuk, Andrei; Rasing, Theo [Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)

    2010-08-15

    Gold nanoparticles (about 10 nm in diameter) are investigated by an apertureless (or scattering-type) scanning near-field optical microscope (aSNOM) at 633 nm and a negative optical amplitude signal contrast is observed. To understand the size effect and the interactions between light, tip, and sample, an analytical solution is obtained by adopting a model considering the tip as a point dipole. This model successfully shows the contrast reversal measured in experiments. Some important aspects, however, are neglected by the quasistatic dipole model. Thus, three-dimensional (3D) numerical calculations by a finite integration technique are applied to study the interactions between tip apex, gold nanoparticle, and the substrate surface. The simulated near-field and far-field results help us not only to understand the experimentally acquired aSNOM images but also to investigate the complicated tip-particle-surface interactions. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  11. Growth of hydroxyapatite on physiologically clotted fibrin capped gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, T P; Sundaraseelan, J; Swarnalatha, K; Sobhana, S S Liji; Makheswari, M Uma; Sekar, S; Mandal, A B [Central Leather Research Institute, Chennai-600020, Tamilnadu (India)], E-mail: sastrytp@hotmail.com, E-mail: abmandal@hotmail.com

    2008-06-18

    The growth of hydroxyapatite (HAp) on physiologically clotted fibrin (PCF)-gold nanoparticles is presented for the first time by employing a wet precipitation method. Fourier transform infrared (FTIR) spectroscopy confirmed the characteristic functionalities of PCF and HAp in the PCF-Au-HAp nanocomposite. Scanning electron microscopy (SEM) images have shown cuboidal nanostructures having a size in the range of 70-300 nm of HAp, whereas 2-50 nm sized particles were visualized in high-resolution transmission electron microscopy (TEM). Energy-dispersive x-ray (EDX) and x-ray diffraction (XRD) studies have confirmed the presence of HAp. These results show that gold nanoparticles with PCF acted as a matrix for the growth of HAp, and that PCF-Au-HAp nanocomposite is expected to have better osteoinductive properties.

  12. The Formation and Binding of Gold Nanoparticles onto Wool Fibres

    Science.gov (United States)

    Johnston, James H.; Burridge, Kerstin A.; Kelly, Fern M.

    2009-07-01

    This paper presents the novel use of nanosize gold with different plasmon resonance colours, as stable colourfast colourants on wool fibres for use in high quality fabrics and textiles. The gold nanoparticles are synthesised by the controlled reduction of Au3+ in the AuCl4- complex to Au0 onto the surface of the wool where they attach to the S in the cystine amino acids in wool keratin proteins. Scanning electronmicroscopy shows the nanoparticles are present on the cuticles of the fibre surface and are concentrated at the edges of these cuticles. EDS analysis shows a strong correlation of Au with S and X-ray photoelectron spectroscopy suggests Au-S bond formation. Hence the nanogold colourants are chemically bound to the wool fibre surface and do not fade as traditional organic dyes do. A range of coloured fibres have been produced.

  13. Towards Effective Photothermal/Photodynamic Treatment Using Plasmonic Gold Nanoparticles.

    Science.gov (United States)

    Bucharskaya, Alla; Maslyakova, Galina; Terentyuk, Georgy; Yakunin, Alexander; Avetisyan, Yuri; Bibikova, Olga; Tuchina, Elena; Khlebtsov, Boris; Khlebtsov, Nikolai; Tuchin, Valery

    2016-08-09

    Gold nanoparticles (AuNPs) of different size and shape are widely used as photosensitizers for cancer diagnostics and plasmonic photothermal (PPT)/photodynamic (PDT) therapy, as nanocarriers for drug delivery and laser-mediated pathogen killing, even the underlying mechanisms of treatment effects remain poorly understood. There is a need in analyzing and improving the ways to increase accumulation of AuNP in tumors and other crucial steps in interaction of AuNPs with laser light and tissues. In this review, we summarize our recent theoretical, experimental, and pre-clinical results on light activated interaction of AuNPs with tissues and cells. Specifically, we discuss a combined PPT/PDT treatment of tumors and killing of pathogen bacteria with gold-based nanocomposites and atomic clusters, cell optoporation, and theoretical simulations of nanoparticle-mediated laser heating of tissues and cells.

  14. Towards Effective Photothermal/Photodynamic Treatment Using Plasmonic Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Alla Bucharskaya

    2016-08-01

    Full Text Available Gold nanoparticles (AuNPs of different size and shape are widely used as photosensitizers for cancer diagnostics and plasmonic photothermal (PPT/photodynamic (PDT therapy, as nanocarriers for drug delivery and laser-mediated pathogen killing, even the underlying mechanisms of treatment effects remain poorly understood. There is a need in analyzing and improving the ways to increase accumulation of AuNP in tumors and other crucial steps in interaction of AuNPs with laser light and tissues. In this review, we summarize our recent theoretical, experimental, and pre-clinical results on light activated interaction of AuNPs with tissues and cells. Specifically, we discuss a combined PPT/PDT treatment of tumors and killing of pathogen bacteria with gold-based nanocomposites and atomic clusters, cell optoporation, and theoretical simulations of nanoparticle-mediated laser heating of tissues and cells.

  15. Dendronized Anionic Gold Nanoparticles: Synthesis, Characterization, and Antiviral Activity.

    Science.gov (United States)

    Peña-González, Cornelia E; García-Broncano, Pilar; Ottaviani, M Francesca; Cangiotti, Michela; Fattori, Alberto; Hierro-Oliva, Margarita; González-Martín, M Luisa; Pérez-Serrano, Jorge; Gómez, Rafael; Muñoz-Fernández, M Ángeles; Sánchez-Nieves, Javier; de la Mata, F Javier

    2016-02-24

    Anionic carbosilane dendrons decorated with sulfonate functions and one thiol moiety at the focal point have been used to synthesize water-soluble gold nanoparticles (AuNPs) through the direct reaction of dendrons, gold precursor, and reducing agent in water, and also through a place-exchange reaction. These nanoparticles have been characterized by NMR spectroscopy, TEM, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, elemental analysis, and zeta-potential measurements. The interacting ability of the anionic sulfonate functions was investigated by EPR spectroscopy with copper(II) as a probe. Different structures and conformations of the AuNPs modulate the availability of sulfonate and thiol groups for complexation by copper(II). Toxicity assays of AuNPs showed that those produced through direct reaction were less toxic than those obtained by ligand exchange. Inhibition of HIV-1 infection was higher in the case of dendronized AuNPs than in dendrons.

  16. Uptake of gold nanoparticles in primary human endothelial cells

    DEFF Research Database (Denmark)

    Klingberg, Henrik; Oddershede, Lene B.; Löschner, Katrin

    2015-01-01

    Gold nanoparticles (AuNPs) are relevant in nanomedicine for drug delivery in the vascular system, where endothelial cells are the first point of contact. We investigated the uptake of 80 nm AuNPs in primary human umbilical vein endothelial cells (HUVECs) by flow cytometry, 3D confocal microscopy....... Uptake of AuNPs in HUVECs occurred mainly by clathrin-mediated endocytosis and trafficking to membrane enclosures in the form of single particles and agglomerates of 2–3 particles....

  17. Various methods of gold nanoparticles (GNPs conjugation to antibodies

    Directory of Open Access Journals (Sweden)

    Mir Hadi Jazayeri

    2016-07-01

    These applications require an increasingly complex level of surface decoration in order to achieve efficacy, and limit off-target toxicity. This review will discuss the chemical and physical approaches commonly utilized in relation to surface decoration and the powerful system used to indicate success of the conjugation. Finally, we review the range of recent studies about covalent and noncovalent modes for conjugation of antibodies to the particle surface that aim to advance gold nanoparticle treatments and diagnostics toward the clinic.

  18. Towards Effective Photothermal/Photodynamic Treatment Using Plasmonic Gold Nanoparticles

    OpenAIRE

    Alla Bucharskaya; Galina Maslyakova; Georgy Terentyuk; Alexander Yakunin; Yuri Avetisyan; Olga Bibikova; Elena Tuchina; Boris Khlebtsov; Nikolai Khlebtsov; Valery Tuchin

    2016-01-01

    Gold nanoparticles (AuNPs) of different size and shape are widely used as photosensitizers for cancer diagnostics and plasmonic photothermal (PPT)/photodynamic (PDT) therapy, as nanocarriers for drug delivery and laser-mediated pathogen killing, even the underlying mechanisms of treatment effects remain poorly understood. There is a need in analyzing and improving the ways to increase accumulation of AuNP in tumors and other crucial steps in interaction of AuNPs with laser light and tissues. ...

  19. Iron oxide and gold nanoparticles in cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Gotman, Irena, E-mail: gotman@technion.ac.il; Gutmanas, Elazar Y., E-mail: gutmanas@technion.ac.il [Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Psakhie, Sergey G. [Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Lozhkomoev, Aleksandr S. [Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2016-08-02

    Continuous research activities in the field of nanomedicine in the past decade have, to a great extent, been focused on nanoparticle technologies for cancer therapy. Gold and iron oxide nanoparticles (NP) are two of the most studied inorganic nanomaterials due to their unique optical and magnetic properties. Both types of NPs are emerging as promising systems for anti-tumor drug delivery and for nanoparticle-mediated thermal therapy of cancer. In thermal therapy, localized heating inside tumors or in proximity of tumor cells can be induced, for example, with Au NPs by radiofrequency ablation heating or conversion of photon energy (photothermal therapy) and in iron oxide magnetic NPs by heat generation through relaxation in an alternating magnetic field (magnetic hyperthermia). Furthermore, the superparamagnetic properties of iron oxide nanoparticles have led to their use as potent MRI (magnetic resonance imaging) contrast agents. Surface modification/coating can produce NPs with tailored and desired properties, such as enhanced blood circulation time, stability, biocompatibility and water solubility. To target nanoparticles to specific tumor cells, NPs should be conjugated with targeting moieties on the surface which bind to receptors or other molecular structures on the cell surface. The article presents several approaches to enhancing the specificity of Au and iron oxide nanoparticles for tumor tissue by appropriate surface modification/functionalization, as well as the effect of these treatments on the saturation magnetization value of iron oxide NPs. The use of other nanoparticles and nanostructures in cancer treatment is also briefly reviewed.

  20. Synthesis of gold and silver nanoparticles using purified URAK.

    Science.gov (United States)

    Deepak, Venkataraman; Umamaheshwaran, Paneer Selvam; Guhan, Kandasamy; Nanthini, Raja Amrisa; Krithiga, Bhaskar; Jaithoon, Nagoor Meeran Hasika; Gurunathan, Sangiliyandi

    2011-09-01

    This study aims at developing a new eco-friendly process for the synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using purified URAK. URAK is a fibrinolytic enzyme produced by Bacillus cereus NK1. The enzyme was purified and used for the synthesis of AuNPs and AgNPs. The enzyme produced AgNPs when incubated with 1 mM AgNO3 for 24 h and AuNPs when incubated with 1 mM HAuCl4 for 60 h. But when NaOH was added, the synthesis was rapid and occurred within 5 min for AgNPs and 12 h for AuNPs. The synthesized nanoparticles were characterized by a peak at 440 nm and 550 nm in the UV-visible spectrum. TEM analysis showed that AgNPs of the size 60 nm and AuNPs of size 20 nm were synthesized. XRD confirmed the crystalline nature of the nanoparticles and AFM showed the morphology of the nanoparticle to be spherical. FT-IR showed that protein was responsible for the synthesis of the nanoparticles. This process is highly simple, versatile and produces AgNPs and AuNPs in environmental friendly manner. Moreover, the synthesized nanoparticles were found to contain immobilized enzyme. Also, URAK was tested on RAW 264.7 macrophage cell line and was found to be non-cytotoxic until 100 μg/ml.

  1. Iron oxide and gold nanoparticles in cancer therapy

    Science.gov (United States)

    Gotman, Irena; Psakhie, Sergey G.; Lozhkomoev, Aleksandr S.; Gutmanas, Elazar Y.

    2016-08-01

    Continuous research activities in the field of nanomedicine in the past decade have, to a great extent, been focused on nanoparticle technologies for cancer therapy. Gold and iron oxide nanoparticles (NP) are two of the most studied inorganic nanomaterials due to their unique optical and magnetic properties. Both types of NPs are emerging as promising systems for anti-tumor drug delivery and for nanoparticle-mediated thermal therapy of cancer. In thermal therapy, localized heating inside tumors or in proximity of tumor cells can be induced, for example, with Au NPs by radiofrequency ablation heating or conversion of photon energy (photothermal therapy) and in iron oxide magnetic NPs by heat generation through relaxation in an alternating magnetic field (magnetic hyperthermia). Furthermore, the superparamagnetic properties of iron oxide nanoparticles have led to their use as potent MRI (magnetic resonance imaging) contrast agents. Surface modification/coating can produce NPs with tailored and desired properties, such as enhanced blood circulation time, stability, biocompatibility and water solubility. To target nanoparticles to specific tumor cells, NPs should be conjugated with targeting moieties on the surface which bind to receptors or other molecular structures on the cell surface. The article presents several approaches to enhancing the specificity of Au and iron oxide nanoparticles for tumor tissue by appropriate surface modification/functionalization, as well as the effect of these treatments on the saturation magnetization value of iron oxide NPs. The use of other nanoparticles and nanostructures in cancer treatment is also briefly reviewed.

  2. Click Chemistry Immobilization of Antibodies on Polymer Coated Gold Nanoparticles.

    Science.gov (United States)

    Finetti, Chiara; Sola, Laura; Pezzullo, Margherita; Prosperi, Davide; Colombo, Miriam; Riva, Benedetta; Avvakumova, Svetlana; Morasso, Carlo; Picciolini, Silvia; Chiari, Marcella

    2016-07-26

    The goal of this work is to develop an innovative approach for the coating of gold nanoparticles (AuNPs) with a synthetic functional copolymer. This stable coating with a thickness of few nanometers provides, at the same time, stabilization and functionalization of the particles. The polymeric coating consists of a backbone of polydimethylacrylamide (DMA) functionalized with an alkyne monomer that allows the binding of azido modified molecules by Cu(I)-catalyzed azide/alkyne 1,3-dipolar cycloaddition (CuAAC, click chemistry). The thin polymer layer on the surface stabilizes the colloidal suspension whereas the alkyne functions pending from the backbone are available for the reaction with azido-modified proteins. The reactivity of the coating is demonstrated by immobilizing an azido modified anti-mouse IgG antibody on the particle surface. This approach for the covalent binding of antibody to a gold-NPs is applied to the development of gold labels in biosensing techniques.

  3. Gold-Pluronic core-shell nanoparticles: synthesis, characterization and biological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Timea; Boca, Sanda [Babes-Bolyai University, Nanobiophotonics and Laser Microspectroscopy Center, Interdisciplinary Research Institute on Bio-Nano-Sciences and Faculty of Physics (Romania); Biro, Dominic [Sapientia University, Department of Mechanical Engineering, Faculty of Technical and Human Sciences (Romania); Baldeck, Patrice [Universite Joseph Fourier and CNRS, Laboratoire Interdisciplinaire de Physique, UMR 5588, CNRS (France); Astilean, Simion, E-mail: simion.astilean@phys.ubbcluj.ro [Babes-Bolyai University, Nanobiophotonics and Laser Microspectroscopy Center, Interdisciplinary Research Institute on Bio-Nano-Sciences and Faculty of Physics (Romania)

    2013-04-15

    This study presents the synthesis of gold-Pluronic core-shell nanoparticles by a two-step method and investigates their biological impact on cancer cells, specifically nanoparticle internalization and cytotoxicity. Uniform, 9-10-nm-sized, hydrophobic gold nanoparticles were synthesized in organic phase by reducing gold salt with oleylamine, after which oleylamine-protected gold nanoparticles were phase-transferred into aqueous medium using Pluronic F127 block copolymer, resulting in gold-Pluronic core-shell nanoparticles with a mean hydrodynamic diameter of {approx}35 nm. The formation and phase-transfer of gold nanoparticles were analyzed by UV-Vis absorption spectroscopy, transmission electron microscopy, and dynamic light scattering. The obtained gold-Pluronic core-shell nanoparticles proved to be highly stable in salted solution. Cytotoxicity tests showed no modification of cellular viability in the presence of properly purified particles. Furthermore, dark-field cellular imaging demonstrated that gold-Pluronic nanoparticles were able to be efficiently uptaken by cells, being internalized through nonspecific endocytosis. The high stability, proven biocompatibility, and imaging properties of gold-Pluronic core-shell nanoparticles hold promise for relevant intracellular applications, with such a design providing the feasibility to combine all multiple functionalities in one nanoparticle for simultaneous detection and imaging.

  4. Bottom-up fabrication of nanohole arrays loaded with gold nanoparticles: extraordinary plasmonic sensors.

    Science.gov (United States)

    Weiler, Markus; Quint, Stefan B; Klenk, Simon; Pacholski, Claudia

    2014-12-18

    A chemical route to periodic hole arrays in gold films whose holes are loaded with single gold nanoparticles is presented, paving the road to mass production of highly sensitive plasmonic sensors on large areas.

  5. Two-dimensional self-organi-zation of 1-nonanethiol-capped gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A two-dimensional (2D) ordered hexagonal close-packed structure, formed by 1-nonanethiol-capped gold nanoparticles, is reported. The structure was constructed only by dipping the gold nanoparticle colloidal solution on flat substrate. The gold nanoparticles were synthesized as follows: First, AuCl4-1 was transferred from aqueous solution to toluene by the phase-transfer reagent of tetraoctylammo-nium bromide. Then it was reduced with aqueous sodium borohydride in the presence of a given amount of 1-nonanethiol molecules which was used to control the nuclea-tion and growth of the gold nanoparticles for the desired size. The experimental techniques, such as UV-Vis, FT-IR, and X-ray photoelectron spectroscopy (XPS), were employed to characterize the obtained product. Transmission electron microscopy (TEM) measurement demonstrated the size of the gold nanoparticle and the formation of two-dimensional ordered hexagonal close-packed gold nanoparticle structure.

  6. Enhancement of R6G fluorescence by N-type porous silicon deposited with gold nanoparticles

    Science.gov (United States)

    Mo, Jia-qing; Jiang, Jing; Zhai, Zhen-gang; Shi, Fu-gui; Jia, Zhen-hong

    2017-01-01

    By the electrochemical anodization method, we achieve the single-layer macroporous silicon on the N-type silicon, and prepare gold nanoparticles with sodium citrate reduction method. Through injecting the gold nanoparticles into the porous silicon by immersion, the fluorescence quenching mechanism of porous silicon influenced by gold nanoparticles is analyzed. Then the macroporous silicon deposited with gold nanoparticles is utilized to enhance the fluorescence of rhodamine 6G (R6G). It is found that when the macroporous silicon is deposited with gold nanoparticles for 6 h, the maximum fluorescence enhancement of R6G (about ten times) can be realized. The N-type porous silicon deposited with gold nanoparticles can be an excellent substrate for fluorescence detection.

  7. [Preparation, characterization and surface-enhanced Raman properties of agarose gel/gold nanoparticles hybrid].

    Science.gov (United States)

    Ma, Xiao-yuan; Liu, Ying; Wang, Zhou-ping

    2014-08-01

    Agarose gel/gold nanoparticles hybrid was prepared by adding gold nanoparticles to preformed agarose gel. Naniocomposite structures and properties were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV-Vis-NIR absorption spectroscopy. Experimental data indicated a uniform distribution of gold nanoparticles adsorbed on agarose gel network And the excellent optical absorption properties were shown. Based on the swelling-contraction characteristics of agarose gel and the adjustable localized surface plasmon resonance (LSPR) of the gold nanoparticles, the nano-composites were used as surface enhanced Raman scattering (SERS) substrate to detect the Raman signal molecules Nile blue A. Results revealed that the porous structure of the agarose gel provided a good carrier for the enrichment of the gold nanoparticles. The gold nanoparticles dynamic hot-spot effect arising from the agarose gel contraction loss of water in the air greatly enhanced the Raman signal.

  8. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by scanning electron microscopy.

    Science.gov (United States)

    Hartsuiker, L; VAN Es, P; Petersen, W; VAN Leeuwen, T G; Terstappen, L W M M; Otto, C

    2011-11-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample preparation protocol was developed to enable imaging of cells and gold nanoparticles with a conventional below lens scanning electron microscopes. The negative influence of 'charging' on the quality of scanning electron microscopes' images could be limited by deposition of biological cells on a conductive (gold) surface. The novel protocol enabled high-resolution scanning electron microscopes' imaging of small clusters and individual gold nanoparticles on uncoated cell surfaces. Gold nanoparticles could be counted on cancer cells with automated routines.

  9. On the thermal conductivity of gold nanoparticle colloids.

    Science.gov (United States)

    Shalkevich, Natallia; Escher, Werner; Bürgi, Thomas; Michel, Bruno; Si-Ahmed, Lynda; Poulikakos, Dimos

    2010-01-19

    Nanofluids (colloidal suspensions of nanoparticles) have been reported to display significantly enhanced thermal conductivities relative to those of conventional heat transfer fluids, also at low concentrations well below 1% per volume (Putnam, S. A., et at. J. Appl. Phys. 2006, 99, 084308; Liu, M.-S. L., et al. Int. J. Heat Mass Transfer. 2006, 49; Patel, H. E., et al. Appl. Phys. Lett. 2003, 83, 2931-2933). The purpose of this paper is to evaluate the effect of the particle size, concentration, stabilization method and particle clustering on the thermal conductivity of gold nanofluids. We synthesized spherical gold nanoparticles of different size (from 2 to 45 nm) and prepared stable gold colloids in the range of volume fraction of 0.00025-1%. The colloids were inspected by UV-visible spectroscopy, transmission electron microscope (TEM) and dynamic light scattering (DLS). The thermal conductivity has been measured by the transient hot-wire method (THW) and the steady state parallel plate method (GAP method). Despite a significant search in parameter space no significant anomalous enhancement of thermal conductivity was observed. The highest enhancement in thermal conductivity is 1.4% for 40 nm sized gold particles stabilized by EGMUDE (triethyleneglycolmono-11-mercaptoundecylether) and suspended in water with a particle-concentration of 0.11 vol%.

  10. Gold nanoparticles supported on magnesium oxide for CO oxidation

    Directory of Open Access Journals (Sweden)

    Bogdanchikova Nina

    2011-01-01

    Full Text Available Abstract Au was loaded (1 wt% on a commercial MgO support by three different methods: double impregnation, liquid-phase reductive deposition and ultrasonication. Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Upon loading with Au, MgO changed into Mg(OH2 (the hydroxide was most likely formed by reaction with water, in which the gold precursor was dissolved. The size range for gold nanoparticles was 2-12 nm for the DIM method and 3-15 nm for LPRD and US. The average size of gold particles was 5.4 nm for DIM and larger than 6.5 for the other methods. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with the DIM method, followed by LPRD and US. This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.

  11. Dual plasmonic gold nanoparticles for multispectral photoacoustic imaging application

    Science.gov (United States)

    Raghavan, Vijay; Subhash, Hrebesh; Breathnach, Aedán.; Leahy, Martin; Dockery, Peter; Olivo, Malini

    2014-03-01

    Nanoparticle contrast agents for molecular targeted imaging have widespread interest in diagnostic applications with cellular resolution, specificity and selectivity for visualization and assessment of various disease processes. Of particular interest is gold nanoparticle owing to its tunability of the surface plasmon resonance (SPR) and its relative inertness. Here we present the synthesis of anisotropic multi-branched star shaped gold nanoparticles exhibiting dual-band plasmon absorption peaks and its application as a contrast agent for multispectral photoacoustic imaging. The transverse plasmon absorption peak of the synthesised dual plasmonic gold nanostar (DPGNS) was around 700 nm and that of longitudinal plasmon absorption in the longer wavelength region around 1050-1150 nm. Unlike most reported PA contrast agent with surface plasmon absorption in the range of 700 to 800 nm showing moderate tissue penetration, 1050-1200 nm range lies in the farther region of the optical window of biological tissue where scattering and the intrinsic optical extinction of endogenous chromophores is at its minimum. We also present a proof of principle demonstration of DPGNS as contrast agent for multispectral photoacoustic animal imaging. Our results show that DPGNS are promising for PA imaging with extended-depth imaging applications.

  12. Protected Gold Nanoparticles with Thioethers and Amines As Surrogate Ligands

    Directory of Open Access Journals (Sweden)

    M. Rafiq H. Siddiqui

    2013-01-01

    Full Text Available Dodecyl sulfide, dodecyl amine, and hexylamine were shown to act as surrogate ligands (L via metastable gold nanoparticles. By collating analytical and spectroscopic data obtained simultaneously, empirical formula Au24L was assigned. These impurity-free nanoparticles obtained in near quantitative yields showing exceptional gold assays (up to 98%Au were prepared by a modification of the two-phase method. Replacement reactions on the Au24L showed that Au:L ratios may be increased (up to Au55:L (L= (H25C122S or decreased (Au12:L (L= H2NC12H25 and H2NC6H13 as desired. This work encompassing the role of analytical techniques used, that is, elemental analysis, variable temperature 1H NMR, FAB mass spectrometry, UV-Vis spectroscopy, thin film X-ray diffraction, and high-resolution electron microscopy (HREM has implications in the study of size control, purity, stability, and metal assays of gold nanoparticles.

  13. Imaging and radiation effects of gold nanoparticles in tumour cells

    Science.gov (United States)

    McQuaid, Harold N.; Muir, Mark F.; Taggart, Laura E.; McMahon, Stephen J.; Coulter, Jonathan A.; Hyland, Wendy B.; Jain, Suneil; Butterworth, Karl T.; Schettino, Giuseppe; Prise, Kevin M.; Hirst, David G.; Botchway, Stanley W.; Currell, Fred J.

    2016-01-01

    Gold nanoparticle radiosensitization represents a novel technique in enhancement of ionising radiation dose and its effect on biological systems. Variation between theoretical predictions and experimental measurement is significant enough that the mechanism leading to an increase in cell killing and DNA damage is still not clear. We present the first experimental results that take into account both the measured biodistribution of gold nanoparticles at the cellular level and the range of the product electrons responsible for energy deposition. Combining synchrotron-generated monoenergetic X-rays, intracellular gold particle imaging and DNA damage assays, has enabled a DNA damage model to be generated that includes the production of intermediate electrons. We can therefore show for the first time good agreement between the prediction of biological outcomes from both the Local Effect Model and a DNA damage model with experimentally observed cell killing and DNA damage induction via the combination of X-rays and GNPs. However, the requirement of two distinct models as indicated by this mechanistic study, one for short-term DNA damage and another for cell survival, indicates that, at least for nanoparticle enhancement, it is not safe to equate the lethal lesions invoked in the local effect model with DNA damage events.

  14. Green Synthesis of Gold and Silver Nanoparticles Using Averrhoa bilimbi Fruit Extract

    OpenAIRE

    Rimal Isaac, R. S.; G Sakthivel; Ch. Murthy

    2013-01-01

    We report on rapid one-step green synthesis of gold and silver nanoparticles using fruit extract of Averrhoa bilimbi Linn. UV-Vis absorption spectroscopy was used to monitor the quantitative formation of gold and silver nanoparticles. The characteristics of the obtained gold and silver nanoparticles were studied using UV-Vis absorption spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Energy-dispersive spectroscopy (EDX). UV/Vis spe...

  15. Curcumin coated gold nanoparticles: synthesis, characterization, cytotoxicity, antioxidant activity and its comparison with citrate coated gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Elnaz Shaabani

    2017-04-01

    Full Text Available Objective(s: Biological applications of gold nanoparticles have limitations because of the toxic chemicals used in their synthesis. Curcumin can be used as reducing as well as capping agent in synthesis of GNPs to eliminate the cytotoxicity. Conjugation of curcumin to gold also helps in increasing its solubility and bioavailability. Materials and Methods: Here we report synthesis of gold nanoparticles coated with citrate and curcumin and of two different sizes via chemical routes. UV-Vis absorbance spectroscopy, Dynamic Light Scattering and Transmission Electron Microscopy were applied to study the average particle size, size stability of the samples and zeta potential. Fourier transform infrared, Raman Spectroscopy and Fluorescence Spectroscopy were applied for detection of curcumin on the surface of GNPs. The antioxidant activity was evaluated using DPPH assay and Cytotoxicity was evaluated by MTT assay.Results: Particles were synthesized of 6 and 16 nm size. The average particle size was found to be 21.7 ± 5.7 by TEM. The zeta potential on the surface of Cur-GNPs was negative and larger than 25 mV which is a sign of their high stability. The stability of these particles (with different coatings but with similar sizes at different time intervals (up to 3 months and also in different media like cell culture medium, different buffers, glucose and at different pH conditions have been investigated thoroughly. Appearance of functional groups assigned to curcumin in FTIR and SERS spectra are sign of presence of curcumin in the sample. The quenching of the fluorescence in the presence of GNPs reveals the clear indication of the capping and binding of curcumin with GNPs. Cur-GNP1 (16 nm were found to exhibit highest antioxidant activity than other gold nanoparticles. Cytotoxicity evaluation using MTT assay on L929 cell line proved curcumin coated gold nanoparticles were non-toxic up to 40 ppm.Conclusion: The results revealed that larger curcumin

  16. Phase transitions and kinetic properties of gold nanoparticles confined between two-layer graphene nanosheets

    Science.gov (United States)

    Wang, Gang; Wu, Nanhua; Chen, Jionghua; Wang, Jinjian; Shao, Jingling; Zhu, Xiaolei; Lu, Xiaohua; Guo, Lucun

    2016-11-01

    The thermodynamic and kinetic behaviors of gold nanoparticles confined between two-layer graphene nanosheets (two-layer-GNSs) are examined and investigated during heating and cooling processes via molecular dynamics (MD) simulation technique. An EAM potential is applied to represent the gold-gold interactions while a Lennard-Jones (L-J) potential is used to describe the gold-GNS interactions. The MD melting temperature of 1345 K for bulk gold is close to the experimental value (1337 K), confirming that the EAM potential used to describe gold-gold interactions is reliable. On the other hand, the melting temperatures of gold clusters supported on graphite bilayer are corrected to the corresponding experimental values by adjusting the εAu-C value. Therefore, the subsequent results from current work are reliable. The gold nanoparticles confined within two-layer GNSs exhibit face center cubic structures, which is similar to those of free gold clusters and bulk gold. The melting points, heats of fusion, and heat capacities of the confined gold nanoparticles are predicted based on the plots of total energies against temperature. The density distribution perpendicular to GNS suggests that the freezing of confined gold nanoparticles starts from outermost layers. The confined gold clusters exhibit layering phenomenon even in liquid state. The transition of order-disorder in each layer is an essential characteristic in structure for the freezing phase transition of the confined gold clusters. Additionally, some vital kinetic data are obtained in terms of classical nucleation theory.

  17. From gold nanoparticles to luminescent nano-objects: experimental aspects for better gold-chromophore interactions

    Science.gov (United States)

    Navarro, Julien R. G.; Lerouge, Frederic

    2017-01-01

    Gold nanoparticles have been the center of interest for scientists since many decades. Within the last 20 years, the research in that field has soared with the possibility to design and study nanoparticles with controlled shapes. From spheres to more complex shapes such as stars, or anisotropic architectures like rods or bipyramids, these new systems feature plasmonic properties making them the tools of choice for studies on light-matter interactions. In that context, fluorescence quenching and enhancement by gold nanostructures is a growing field of research. In this review, we report a non-exhaustive summary of the synthetic modes for various shapes and sizes of isotropic and anisotropic nanoparticles. We then focus on fluorescent studies of these gold nano-objects, either considering "bare" particles (without modifications) or hybrid particles (surface interaction with a chromophore). In the latter case, the well-known metal-enhanced fluorescence (MEF) is more particularly developed; the mechanisms of MEF are discussed in terms of the additional radiative and non-radiative decay rates caused by several parameters such as the vicinity of the chromophore to the metal or the size and shape of the nanostructures.

  18. Oxidation of bioethanol using zeolite-encapsulated gold nanoparticles.

    Science.gov (United States)

    Mielby, Jerrik; Abildstrøm, Jacob Oskar; Wang, Feng; Kasama, Takeshi; Weidenthaler, Claudia; Kegnaes, Søren

    2014-11-10

    With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite-1 is reported and their high activity and selectivity for the catalytic gas-phase oxidation of ethanol are demonstrated. The zeolites are modified by a recrystallization process, which creates intraparticle voids and mesopores that facilitate the formation of small and disperse nanoparticles upon simple impregnation. The individual zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2-3 nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50 % conversion of ethanol with 98 % selectivity toward acetaldehyde at 200 °C, which (under the given reaction conditions) corresponds to 606 mol acetaldehyde/mol Au hour(-1) .

  19. Self-assembly of lysozyme on the surfaces of gold nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Ming Hui Xiang; Xiao Xu; Na Li; Ke An Li

    2011-01-01

    The interaction of lysozyme (Lys) and gold nanoparticles was investigated via UV-vis absorption and resonance light-scattering method. There are some changes of the plasmon absorption and resonance light-scattering of gold nanoparticles that were observed via the addition of Lys. The normalized plasmon absorption and resonance light-scattering intensity with gold nanoparticles were both linear with 1-20 nmol/L Lys. A simple model about the component of the gold nanoparticles and Lys complex was established and the calculated result was fitted well in their concentration ratio. Furthermore, the activity analysis of Lys showed that the interaction was weak and nondestructive.

  20. Comparison of galvanic displacement and electroless methods for deposition of gold nanoparticles on synthetic calcite

    Indian Academy of Sciences (India)

    Chamarthi K Srikanth; P Jeevanandam

    2012-11-01

    Gold nanoparticles have been deposited on synthetic calcite substrate by galvanic displacement reaction and electroless deposition methods. A comparative study has shown that electroless deposition is superior compared to galvanic displacement reaction for uniform deposition of gold nanoparticles on calcite. Characterization of the samples, prepared by two different deposition methods, was carried out by X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy (FE–SEM) and diffuse reflectance spectroscopy (DRS) measurements. FE–SEM studies prove that smaller nanoparticles of gold are deposited uniformly on calcite if electroless deposition method was employed and DRS measurements show the characteristic surface plasmon resonance of gold nanoparticles.

  1. Coalescence and Collisions of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Eduardo Pérez-Tijerina

    2011-01-01

    Full Text Available We study the assembling of small gold clusters subject to collisions and close contact coalescence by using molecular dynamics simulations to simulate events that occur typically in the sputtering process of synthesis. Our results support the notion that the kinetics of coalescence processes strongly determine the geometry and structure of the final particle. While impact velocities, relative orientations, and the initial shape of the interacting particles are unlikely to strictly determine the structural details of the newly formed particle, we found that high initial temperatures and/or impact velocities increase the probability of appearance of icosahedral-like structures, Wulff polyhedra are likely to be formed as a product of the interactions between nanospheres, while the appearance of fcc particles of approximately cuboctahedral shape is mainly due to the interaction between icosahedra.

  2. Synthesis and characterization of gold nanoparticles using Ficus religiosa extract

    Directory of Open Access Journals (Sweden)

    Kirtee Wani

    2013-03-01

    Full Text Available We report a cost effective and eco-friendly biosynthesis of gold nanoparticles (F-AuNPs using aqueous extract of Ficus religiosa as the reducing and stabilizing agent. These nanoparticles were characterized by various techniques such as UV-Vis, XRD, TEM and FTIR. The characteristic surface plasmon peak was observed at 540 nm while XRD analysis suggested it to be a face-centered cubic (fcc structure with peaks at 38.06, 44.46, 64.75 and 77.56. FTIR studies indicated the capping of the nanoparticles with polyphenols, amines and carboxylates present in the extract of Ficus religiosa whereas TEM analysis showed spherical morphology with other shapes such as triangles and hexagons. The F-AuNPs were found to be non-toxic to HEK 293 cells, thereby suggesting their potential application in the field of nanobiotechnology.

  3. Label-free gold nanoparticles for the determination of neomycin

    Science.gov (United States)

    Apyari, Vladimir V.; Dmitrienko, Stanislava G.; Arkhipova, Viktoriya V.; Atnagulov, Aydar G.; Gorbunova, Mariya V.; Zolotov, Yury A.

    2013-11-01

    A new spectrophotometric method for the determination of neomycin has been developed. The method is based on aggregation of label-free gold nanoparticles leading to change in absorption spectra and color of the solution. Influence of different factors (the concentration of ethylenediaminetetraacetate (EDTA), pH, the concentrations of neomycin and the nanoparticles) on the aggregation and analytical performance of the method was investigated. EDTA plays an important role not only as a masking agent to eliminate interferences of metal cations but strongly affects the sensitivity of the nanoparticles relative to neomycin. The method allows to determine neomycin with detection limit of 28 ng mL-1. It was applied to analysis of eye- and ear-drops. The sample pretreatment is simply done by diluting the formulation with water.

  4. Size evolution of gold nanoparticles in a millifluidic reactor.

    Science.gov (United States)

    Li, Yuehao; Sanampudi, Ashwin; Raji Reddy, Vanga; Biswas, Sanchita; Nandakumar, Krishnaswamy; Yemane, Dawit; Goettert, Jost; Kumar, Challa S S R

    2012-01-16

    The size evolution of gold nanoparticles in a millifluidic reactor is investigated using spatially resolved transmission electron microscopy (TEM). The experimental data is supported by numerical simulations, carried out to study the residence-time distribution (RTD) of tracers that have the same properties as Au ions. Size and size distribution of the particles within the channels are influenced by the mixing zones as well as the RTD. However, the Au nanoparticles obtained show a broader size distribution even at the shortest investigated residence time of 3.53 s, indicating that in addition to surface growth reaction kinetics also plays an important role. The comparison of time resolved particle growth within the millifluidic channel with flask-based reactions reveals that the particle size can be controlled better within millifluidic channels. Overall, the results indicate potential opportunities to utilize easy to fabricate millifluidic reactors for the synthesis of nanoparticles, as well as as for carrying out time resolved kinetic studies.

  5. Gold Nanoparticles Decorated with Mannose-6-phosphate Analogues

    Directory of Open Access Journals (Sweden)

    Stéphanie Combemale

    2014-01-01

    Full Text Available Herein, the preparation of neoglycoconjugates bearing mannose-6-phosphate analogues is described by: (a synthesis of a cyclic sulfate precursor to access the carbohydrate head-group by nucleophilic displacement with an appropriate nucleophile; (b introduction of spacers on the mannose-6-phosphate analogues via Huisgen’s cycloaddition, the Julia reaction, or the thiol-ene reaction under ultrasound activation. With the resulting compounds in hand, gold nanoparticles could be functionalized with various carbohydrate derivatives (glycoconjugates and then tested for angiogenic activity. It was observed that the length and flexibility of the spacer separating the sugar analogue from the nanoparticle have little influence on the biological response. One particular nanoparticle system substantially inhibits blood vessel growth in contrast to activation by the corresponding monomeric glycoconjugate, thereby demonstrating the importance of multivalency in angiogenic activity.

  6. Preparation of gold nanoparticle dimers via streptavidin-induced interlinking

    Energy Technology Data Exchange (ETDEWEB)

    Zon, Vera B.; Sachsenhauser, Matthias; Rant, Ulrich, E-mail: rant@wsi.tum.de [Technische Universitaet Muenchen, Walter Schottky Institut (Germany)

    2013-10-15

    There is great interest in establishing efficient means of organizing nanoparticles into complex structures, especially in fields like nano-optical devices. One of the demonstrated routes uses biomolecular scaffolds, like the streptavidin-biotin system, to deterministically separate and structure particle complexes. However, controlled formation of streptavidin-linked nanoparticle dimers or trimers is challenging, and large aggregates are often formed under conditions that are difficult to regulate. Here, we studied the aggregates and interlinking kinetics of biotin-functionalized 20 nm gold nanoparticles in the presence of the interlinking protein, streptavidin. We found two different protein-linker concentration regions where small stable particle aggregates are formed: when the protein and nanoparticle concentrations are similar and when the protein to nanoparticle concentration ratio exceeds intermediate concentrations (10:1-100:1) that promote precipitation of large aggregates. We attribute this behavior to the limited availability of free-linker molecules and the limited availability of free ligand (biotin) on the particle surface for low and high protein concentrations, respectively. Furthermore, we show that the product can be additionally enriched up to 25 % through either centrifugation in sucrose or size-exclusion chromatography. These results provide additional understanding into the assembly of ligand-functionalized nanoparticles with water-soluble linkers and provide a facile way to produce well-defined small aggregates for potential use in, for instance, surface-enhanced spectroscopy.

  7. Sub-10 ohm resistance gold films prepared by removal of ligands from thiol-stabilized 6 nm gold nanoparticles.

    Science.gov (United States)

    Sugden, Mark W; Richardson, Tim H; Leggett, Graham

    2010-03-16

    The optical and electrical properties of dodecanethiol-stabilized nanoparticles (6 nm diameter gold core) have been investigated over a range of film thicknesses and temperatures. The surface plasmon resonance absorbance is found to be dependent on temperature. Heating of the nanoparticle film causes desorption of the thiol from the surface of the gold nanoparticle, resulting in irreversible changes to the absorption spectra of the nanoparticle film. Atomic force microscopy images of the samples before and after heating for different film thicknesses reveal structural changes and increased domain connectivity for thicker films leading to sub-10 ohm resistances measured for the 15-layer film.

  8. Investigating the Toxicity, Uptake, Nanoparticle Formation and Genetic Response of Plants to Gold

    Science.gov (United States)

    Taylor, Andrew F.; Rylott, Elizabeth L.; Anderson, Christopher W. N.; Bruce, Neil C.

    2014-01-01

    We have studied the physiological and genetic responses of Arabidopsis thaliana L. (Arabidopsis) to gold. The root lengths of Arabidopsis seedlings grown on nutrient agar plates containing 100 mg/L gold were reduced by 75%. Oxidized gold was subsequently found in roots and shoots of these plants, but gold nanoparticles (reduced gold) were only observed in the root tissues. We used a microarray-based study to monitor the expression of candidate genes involved in metal uptake and transport in Arabidopsis upon gold exposure. There was up-regulation of genes involved in plant stress response such as glutathione transferases, cytochromes P450, glucosyl transferases and peroxidases. In parallel, our data show the significant down-regulation of a discreet number of genes encoding proteins involved in the transport of copper, cadmium, iron and nickel ions, along with aquaporins, which bind to gold. We used Medicago sativa L. (alfalfa) to study nanoparticle uptake from hydroponic culture using ionic gold as a non-nanoparticle control and concluded that nanoparticles between 5 and 100 nm in diameter are not directly accumulated by plants. Gold nanoparticles were only observed in plants exposed to ionic gold in solution. Together, we believe our results imply that gold is taken up by the plant predominantly as an ionic form, and that plants respond to gold exposure by up-regulating genes for plant stress and down-regulating specific metal transporters to reduce gold uptake. PMID:24736522

  9. Investigating the toxicity, uptake, nanoparticle formation and genetic response of plants to gold.

    Directory of Open Access Journals (Sweden)

    Andrew F Taylor

    Full Text Available We have studied the physiological and genetic responses of Arabidopsis thaliana L. (Arabidopsis to gold. The root lengths of Arabidopsis seedlings grown on nutrient agar plates containing 100 mg/L gold were reduced by 75%. Oxidized gold was subsequently found in roots and shoots of these plants, but gold nanoparticles (reduced gold were only observed in the root tissues. We used a microarray-based study to monitor the expression of candidate genes involved in metal uptake and transport in Arabidopsis upon gold exposure. There was up-regulation of genes involved in plant stress response such as glutathione transferases, cytochromes P450, glucosyl transferases and peroxidases. In parallel, our data show the significant down-regulation of a discreet number of genes encoding proteins involved in the transport of copper, cadmium, iron and nickel ions, along with aquaporins, which bind to gold. We used Medicago sativa L. (alfalfa to study nanoparticle uptake from hydroponic culture using ionic gold as a non-nanoparticle control and concluded that nanoparticles between 5 and 100 nm in diameter are not directly accumulated by plants. Gold nanoparticles were only observed in plants exposed to ionic gold in solution. Together, we believe our results imply that gold is taken up by the plant predominantly as an ionic form, and that plants respond to gold exposure by up-regulating genes for plant stress and down-regulating specific metal transporters to reduce gold uptake.

  10. PST-Gold nanoparticle as an effective anticancer agent with immunomodulatory properties.

    Science.gov (United States)

    Joseph, Manu M; Aravind, S R; Varghese, Sheeja; Mini, S; Sreelekha, T T

    2013-04-01

    Polysaccharide PST001, which is isolated from the seed kernels of Tamarindus indica (Ti), is an antitumor and immunomodulatory compound. Gold nanoparticles have been used for various applications in cancer. In the present report, a novel strategy for the synthesis and stabilization of gold nanoparticles using anticancer polysaccharide PST001 was employed and the nanoparticles' antitumor activity was evaluated. PST-Gold nanoparticles were prepared such that PST001 acted both as a reducing agent and as a capping agent. PST-Gold nanoparticles showed high stability, no obvious aggregation for months and a wide range of pH tolerance. PST-Gold nanoparticles not only retained the antitumor effect of PST001 but also showed an enhanced effect even at a low concentration. It was also found that the nanoparticles exerted their antitumor effects through the induction of apoptosis. In vivo assays on BALB/c mice revealed that PST-Gold nanoparticles exhibited immunomodulatory effects. Evaluation of biochemical, hematological and histopathological features of mice revealed that PST-Gold nanoparticles could be administered safely without toxicity. Using the polysaccharide PST001 for the reduction and stabilization of gold nanoparticles does not introduce any environmental toxicity or biological hazards, and these particles are more effective than the parent polysaccharide. Further studies should be employed to exploit these particles as anticancer agents with imaging properties.

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

    Science.gov (United States)

    Basavegowda, Nagaraj; Lee, Yong Rok

    2014-06-01

    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.

  12. Phytogenic silver, gold, and bimetallic nanoparticles as novel antitubercular agents.

    Science.gov (United States)

    Singh, Richa; Nawale, Laxman; Arkile, Manisha; Wadhwani, Sweety; Shedbalkar, Utkarsha; Chopade, Snehal; Sarkar, Dhiman; Chopade, Balu Ananda

    2016-01-01

    Multi- and extensively drug-resistant tuberculosis (TB) is a global threat to human health. It requires immediate action to seek new antitubercular compounds and devise alternate strategies. Nanomaterials, in the present scenario, have opened new avenues in medicine, diagnosis, and therapeutics. In view of this, the current study aims to determine the efficacy of phytogenic metal nanoparticles to inhibit mycobacteria. Silver (AgNPs), gold (AuNPs), and gold-silver bimetallic (Au-AgNPs) nanoparticles synthesized from medicinal plants, such as Barleria prionitis, Plumbago zeylanica, and Syzygium cumini, were tested against Mycobacterium tuberculosis and M. bovis BCG. In vitro and ex vivo macrophage infection model assays were designed to determine minimum inhibitory concentration (MIC) and half maximal inhibitory concentration of nanoparticles. Microscopic analyses were carried out to demonstrate intracellular uptake of nanoparticles in macrophages. Besides this, biocompatibility, specificity, and selectivity of nanoparticles were also established with respect to human cell lines. Au-AgNPs exhibited highest antitubercular activity, with MIC of nanoparticles were capable of entering macrophage cells and exhibited up to 45% cytotoxicity at 30 μg/mL (ten times MIC concentration) after 48 hours. Among these, Au-AgNPs synthesized from S. cumini were found to be more specific toward mycobacteria, with their selectivity index in the range of 94-108. This is the first study to report the antimycobacterial activity of AuNPs, AgNPs, and Au-AgNPs synthesized from medicinal plants. Among these, Au-AgNPs from S. cumini showed profound efficiency, specificity, and selectivity to kill mycobacteria. These should be investigated further to develop novel TB nanoantibiotics.

  13. Interferometric detection of single gold nanoparticles calibrated against TEM size distributions

    DEFF Research Database (Denmark)

    Zhang, Lixue; Christensen, Sune; Bendix, Pól Martin

    2015-01-01

    Single nanoparticle analysis: An interferometric optical approach calibrates sizes of gold nanoparticles (AuNPs) from the interference intensities by calibrating their interferometric signals against the corresponding transmission electron microscopy measurements. This method is used to investigate...

  14. Investigation of Electrochemical Charging Behaviors of "Naked" Gold Nanoparticles Ensembles in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    CHENG,Wen-Long(程文龙); HAN,Xiao-Jun(韩晓军); PENG,Zhang-Quan(彭章泉); DOGN,Shao-Jun(董绍俊); WANG,Er-Kang(汪尔康)

    2002-01-01

    Gold nanoparticles were immobilized onto the electrode surface by simple self-assembly technique. Interestingly, the ensmbles of these nanoparticles exhibit quantized charging behaviors in aqueous solution. Possible mechanism for such behaviors was proposed.

  15. Investigation of Electrochemical Charging Behaviors of“Naked” Gold Nanoparticles Ensembles in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    程文龙; 韩晓军; 彭章泉; 董绍俊; 汪尔康

    2002-01-01

    Gold nanoparticles were imnoobilized onto the electrode surface by simple self-assembly technique.Interestingly,the ensembles of these nanoparticles exhibit quantized charging behaviors in aqueous solution.Possible mechanism for such behaviors was proposed.

  16. Directed assembly of gold nanowires on silicon via reorganization and simultaneous fusion of randomly distributed gold nanoparticles.

    Science.gov (United States)

    Reinhardt, Hendrik M; Bücker, Kerstin; Hampp, Norbert A

    2015-05-04

    Laser-induced reorganization and simultaneous fusion of nanoparticles is introduced as a versatile concept for pattern formation on surfaces. The process takes advantage of a phenomenon called laser-induced periodic surface structures (LIPSS) which originates from periodically alternating photonic fringe patterns in the near-field of solids. Associated photonic fringe patterns are shown to reorganize randomly distributed gold nanoparticles on a silicon wafer into periodic gold nanostructures. Concomitant melting due to optical heating facilitates the formation of continuous structures such as periodic gold nanowire arrays. Generated patterns can be converted into secondary structures using directed assembly or self-organization. This includes for example the rotation of gold nanowire arrays by arbitrary angles or their fragmentation into arrays of aligned gold nanoparticles.

  17. Toxicological risk assessment of elemental gold following oral exposure to sheets and nanoparticles – A review

    DEFF Research Database (Denmark)

    Hadrup, Niels; Sharma, Anoop Kumar; Poulsen, Morten

    2015-01-01

    Elemental gold is used as a food coloring agent and in dental fillings. In addition, gold nanoparticles are gaining increasing attention due to their potential use as inert carriers for medical purposes. Although elemental gold is considered to be inert, there is evidence to suggest the release...... of gold ions from its surface. Elemental gold, or the released ions, is, to some extent, absorbed in the gastrointestinal tract. Gold is distributed to organs such as the liver, heart, kidneys and lungs. The main excretion route of absorbed gold is through urine. Data on the oral toxicity of elemental...... gold is limited. The acute toxicity of elemental gold seems to be low, as rats were unaffected by a single dose of 2000mg nanoparticles/kg of body weight. Information on repeated dose toxicity is very limited. Skin rashes have been reported in humans following the ingestion of liquors containing gold...

  18. Biosynthesis of gold nanoparticles using streptomyces fulvissimus isolate

    Directory of Open Access Journals (Sweden)

    Meysam Soltani Nejad

    2015-04-01

    Full Text Available Objective(s: In recent years, the biosynthesis of gold nanoparticles has been the focus of interest because of their emerging application in a number of areas such as biomedicine. In the present study we report the extracellular biosynthesis of gold nanoparticles (AuNPs by using a positive bacterium named Streptomyces fulvissimus isolate U from rice fields of Guilan Province, Iran. Materials and Methods: From over 20 Streptomyces isolates collected, isolate U showed high AuNPs biosynthesis activity. To determine its taxonomical identity, its morphology was characterized by scanning electron microscope and partial molecular analysis performed by PCR. In this regard, 16S rDNA of isolate U was amplified using universal bacterial primers FD1 and RP2. The PCR products were purified and sequenced. Sequence analysis of 16S rDNA was then conducted using NCBI BLAST method. In biosynthesis of AuNPs by this bacterium, the biomass of bacterium exposed to the HAuCl4 solution. Results: The nanoparticles obtained were characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM and Energy dispersive X-ray (EDX spectroscopy and X-ray diffraction spectroscopy (XRD analyses. Our results indicated that Streptomyces fulvissimus isolateU bio-synthesizes extracellular AuNPs in the range of 20-50 nm. Conclusions: This technique of green synthesis of AuNPs by a microbial source may become a promising method because of its environmental safety. Its optimization may make it a potential procedure for industrial production of gold nanoparticles.

  19. Gold and silver nanoparticles from Trianthema decandra: synthesis, characterization, and antimicrobial properties

    Directory of Open Access Journals (Sweden)

    Geethalakshmi R

    2012-10-01

    Full Text Available R Geethalakshmi, DVL SaradaDepartment of Biotechnology, School of Bioengineering, Sri Ramaswamy Memorial University, Kattankulathur, Tamil Nadu, IndiaBackground: There is an increasing commercial demand for nanoparticles due to their wide applicability in various markets, including medicine, catalysis, electronics, chemistry, and energy. In this report, a simple and ecofriendly chemical reaction for the synthesis of gold and silver nanoparticles from Trianthema decandra (Aizoaceae has been developed.Methods and results: On treatment of aqueous solutions containing chloroauric acid or silver nitrate with root extract of T. decandra, stable gold or silver nanoparticles were rapidly formed. The kinetics of reduction of gold and silver ions during the reaction was analyzed by ultraviolet-visible spectroscopy. Field emission-scanning electron microscopy showed formation of gold nanoparticles in various shapes, including spherical, cubical, triangular, and hexagonal, while silver nanoparticles were spherical. The size of the gold nanoparticles was 33–65 nm and that of the silver nanoparticles was 36–74 nm. Energy dispersive x-ray and Fourier transform infrared spectroscopy confirmed the presence of metallic gold and metallic silver in the respective nanoparticles. The antimicrobial properties of the synthesized nanoparticles were analyzed using the Kirby-Bauer method. The results show varied susceptibility of microorganisms to the gold and silver nanoparticles.Conclusion: It is believed that phytochemicals present in T. decandra extract reduce the silver and gold ions into metallic nanoparticles. This strategy reduces the cost of production and the environmental impact. The silver and gold nanoparticles formed showed strong activity against all microorganisms tested.Keywords: Trianthema decandra, gold, silver, nanoparticles, antimicrobial activity

  20. Gold nanoparticle wire and integrated wire array for electronic detection of chemical and biological molecules

    Directory of Open Access Journals (Sweden)

    J. J. Diao

    2011-03-01

    Full Text Available Nanoparticle wire and integrated nanoparticle wire array have been prepared through a green technique: discontinuous vertical evaporation-driven colloidal deposition. The conducting gold nanoparticle wire made by this technique shows ability for the sensitive electronic detection of chemical and biological molecules due to its high surface to volume ratio. Furthermore, we also demonstrate a potential usage of integrated gold nanoparticle wire array for the localized detection.

  1. An in-vitro studies on green synthesis of gold nanoparticles against pathogens and cancer cells

    Directory of Open Access Journals (Sweden)

    V. Ramesh

    2015-11-01

    Full Text Available Nanotechnology is a most promising field for generating new applications in medicine. It is imperative to integrate nanoscience and medicine. The present investigation is highly warranted to through more light upon the gold nanoparticles reduced from gold salt through the active principle of medicinal plant. The special emphasis of investigation is the active principle along with gold nanoparticles against for cancer cells. The 70 - 90 nm sized particles were synthesized by using Diospyros ferrea and this confirmed by SEM. These gold nanoparticles showed a characteristic absorption peak at 540 nm in UV spectra. The possibility of protein as a stabilizing material in gold nanoparticles is revealed by FTIR analysis. Remarkably, as a result of wide screening on the application of newly synthesized gold nanoparticles their anticancer potential has been discovered using MTT assay. The antimicrobial activity of AuNPs showed effective against bacteria than the fungal strains.

  2. Gold Nanoparticles Generated in Ethosome Bilayers, As Revealed by Cryo-Electron-Tomography

    CERN Document Server

    de la Presa, Patricia; Morales, Maria del Puerto; Chichon, F Javier; Arranz, Rocio; Valpuesta, Jose Maria; Hernando, Antonio; 10.1021/jp808650e

    2009-01-01

    Gold nanoparticles have been synthesized inside ethosomes, vesicles composed of phospholipid, ethanol and water, which could be very efficient not only in delivery probes to the skin but also as diagnostic and therapeutic multimodal agents. High efficiency encapsulation of gold nanoparticles is achieved by a simple strategy: the nanoparticles synthesis occurs simultaneously with the ethosomes formation, in the absence of any undesirable reducing agents. A three-dimensional reconstruction of a gold-embedded ethosome generated by cryoelectron tomography reveals that the gold particle is localized inside the lipid bilayer, leaving the ethosome surface and core free for further functionalization. The resulting gold nanoparticles are homogeneous in size and shape and, depending on synthesis temperature, the size ranges from 10 to 20 nm, as revealed by TEM. The ethosome-nanoparticles hybrids size has been investigated by means of dynamic light scattering and has been found to vary with temperature and gold salt con...

  3. Comparison of Gold Nanoparticle Conjugated Secondary Antibody with Non-Gold Secondary Antibody in an ELISA Kit Model.

    Science.gov (United States)

    Emami, Tara; Madani, Rasool; Golchinfar, Fariba; Shoushtary, Abdolhamid; Amini, Seyed Mohammad

    2015-10-01

    In this study, gold nanoparticles (AuNPs) were used as carriers of the signaling anti-chicken antibody peroxidase in comparison with anti-chicken antibody peroxidase without gold nanoparticle in a commercial avian influenza kit. AuNPs enhanced the absorbance and shortened the assay time. AuNPs act as a carrier of many enzymes and multiply the effect of enzyme when reacting with substrate. They amplify optical signal, while keeping low background signals.

  4. Facile green synthesis of variable metallic gold nanoparticle using Padina gymnospora, a brown marine macroalga

    Science.gov (United States)

    Singh, M.; Kalaivani, R.; Manikandan, S.; Sangeetha, N.; Kumaraguru, A. K.

    2013-04-01

    The process of development of reliable and eco-friendly metallic nanoparticles is an important step in the field of nanotechnology. To achieve this, use of natural sources like biological systems becomes essential. In the present work, extracellular biosynthesis of gold nanoparticles using Padina gymnospora has been attempted and achieved rapid formation of gold nanoparticles in a short duration. The UV-vis spectrum of the aqueous medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. Scanning electron microscopy showed the formation of well-dispersed gold nanoparticles. FTIR spectra of brown alga confirmed that hydroxyl groups present in the algal polysaccharides were involved in the gold bioreduction. AFM analysis showed the results of particle sizes (53-67 nm) and average height of the particle roughness (60.0 nm). X-ray diffraction (XRD) spectrum of the gold nanoparticles exhibited Bragg reflections corresponding to gold nanoparticles. This environment-friendly method of biological gold nanoparticle synthesis can be applied potentially in various products that directly come in contact with the human body, such as cosmetics, and foods and consumer goods, besides medical applications.

  5. Rapid green synthesis of gold nanoparticles using Rosa hybrida petal extract at room temperature.

    Science.gov (United States)

    Noruzi, Masumeh; Zare, Davood; Khoshnevisan, Kamyar; Davoodi, Daryoush

    2011-09-01

    This study reports a green method for the synthesis of gold nanoparticles using the aqueous extract of rose petals. The effects of gold salt concentration, extract concentration and extract quantity were investigated on nanoparticles synthesis. Gold nanoparticles were characterized with different techniques such as UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, dynamic light scattering and transmission electron microscopy. Transmission electron microscopy experiments showed that these nanoparticles are formed with various shapes. FT-IR spectroscopy revealed that gold nanoparticles were functionalized with biomolecules that have primary amine group (-NH2), carbonyl group, -OH groups and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face centered cubic structure of gold nanoparticles. Dynamic light scattering technique was used for particle size measurement, and it was found to be about 10nm. The rate of the reaction was high and it was completed within 5 min.

  6. Biosynthesis and characterization of gold nanoparticles using extracts of tamarindus indica L leaves

    Science.gov (United States)

    Correa, S. N.; Naranjo, A. M.; Herrera, A. P.

    2016-02-01

    This study reports the biosynthesis of gold nanoparticles using an extract of Tamarindus indica L. leaves. Phenols, ketones and carboxyls were present in the leaves of T. indica. These organic compounds that allowed the synthesis of nanoparticles were identified by gas chromatography coupled to mass spectrometry (GC/MS) and High Pressure Liquid Chromatographic (HPLC). Synthesis of gold nanoparticles was performed with the extract of T. indica leaves and an Au+3 aqueous solutions (HAuCl4) at room temperature with one hour of reaction time. Characterization of gold nanoparticles was performed by UV visible spectroscopy, scanning electron microscopy (SEM) and EDX. The results indicated the formation of gold nanoparticles with a wavelength of 576nm and an average size of 52±5nm. The EDX technique confirmed the presence of gold nanoparticles with 12.88% in solution.

  7. Gold-Speckled Multimodal Nanoparticles for Noninvasive Bioimaging

    Science.gov (United States)

    2008-01-01

    In this report the synthesis, characterization, and functional evaluation of a multimodal nanoparticulate contrast agent for noninvasive imaging through both magnetic resonance imaging (MRI) and photoacoustic tomography (PAT) is presented. The nanoparticles described herein enable high resolution and highly sensitive three-dimensional diagnostic imaging through the synergistic coupling of MRI and PAT capabilities. Gadolinium (Gd)-doped gold-speckled silica (GSS) nanoparticles, ranging from 50 to 200 nm, have been prepared in a simple one-pot synthesis using nonionic microemulsions. The photoacoustic signal is generated from a nonuniform, discontinuous gold nanodomains speckled across the silica surface, whereas the MR contrast is provided through Gd incorporated in the silica matrix. The presence of a discontinuous speckled surface, as opposed to a continuous gold shell, allows sufficient bulk water exchange with the Gd ions to generate a strong MR contrast. The dual imaging capabilities of the particles have been demonstrated through in silicio and in vitro methods. The described particles also have the capacity for therapeutic applications including the thermal ablation of tumors through the absorption of irradiated light. PMID:19466201

  8. Eco-Friendly Synthesis of Fucoidan-Stabilized Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kriengsak Lirdprapamongkol

    2010-01-01

    Full Text Available Problem statement: Metallic gold nanoparticles (AuNPs are widely used in many applications including medical, pharmaceutical, diagnostics and sensors. The chemical synthesis of AuNPs normally requires synthetic materials which might cause the toxicological concerns. The use of naturally occurring materials like fucoidans for successful synthesis of AuNPs is of interests. Approach: Fucoidans as sulfated polysaccharides from marine algae Cladosiphon okamuranus (o-fucoidan and Kjellamaniella crassifolia (t-fucoidan were used for synthesis of AuNPs. The suitable condition for the synthesis was investigated to obtain the nanometric size of AuNPs. The synthesized AuNPs were characterized for the size, morphology and Surface Plasmon Resonance (SPR. Results: The fucoidan-stabilized AuNPs containing optimum weight ratio of gold atom to fucoidan yielded the spherical sizes with an average of 8-10 nm and the absorption maxima of SPR band around 527-530 nm. The AuNPs stabilized by o-fucoidan structured as linear polymer were more monodisperse than those stabilized by t-fucoidan structured as branched polymer. Conclusion: Fucoidan can be employed solely for AuNP synthesis and the sulfate constituent in fucoidan is important for gold reduction and stabilization. The simple yet eco-friendly synthesis of AuNPs stabilized by fucoidans would be attractive for application use of metallic nanoparticles.

  9. SYNTHESIS AND CHARACTERIZATION OF GOLD NANOPARTICLES BY JUSTICIA GENDARUSSA BURM F. LEAF EXTRACT

    Directory of Open Access Journals (Sweden)

    Ponnuswamy Renuka Devi et al.

    2012-02-01

    Full Text Available The unusual physio and chemical properties of gold nanoparticles are found to have more advantage in the field of medicine, diagnostics and biosensors. In the present document, it is reported that Justicia gendarussa leaf extract mediated synthesis of gold nanoparticles by the reduction of gold ions. Three different phytochemical fractions were prepared from methanolic leaf extract by liquid-liquid extraction method using immiscible solvents. The total polyphenols, flavonoids and electron donating capacity (DPPH assay of each phytochemical fraction was analyzed. The 1mg/ml of diethyl ether phytochemical fraction produced more gold nanoparticles within 15 minutes when exposed to 10ml of 0.5mM chloroauric acid compared to chloroform and ethyl acetate phytochemical fractions. The structural characteristics of diethyl ether phytochemical fraction synthesized gold nanoparticles were characterized by UV-visible spectroscopy, Dynamic light scattering, Transmission electron microscopy, X-ray diffraction and Fourier transform-infrared spectroscopies. These biosynthesized gold nanoparticles showed surface plasmon resonance band at 536nm in UV-visible spectrum. The size of the gold nanoparticles ranged from 20 to 42nm and 62 to 88nm with spherical, triangle, truncated triangle and hexagonal shapes. From the Fourier transform-infrared spectra of diethyl ether phytochemical fraction and synthesized gold nanoparticles, the possible functional group involved in gold ions reduction and capping of gold nanoparticles were identified. The stability of gold nanoparticles for 5 month period and at different pH range (5-10 was analyzed by observing the changes in surface plasmon resonance of gold nanoparticles. Moreover, the diethyl ether phytochemical fraction showed no cytotoxicity up to 100μg/ml in RAW 264.7 cell line .

  10. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    Science.gov (United States)

    dos Santos, Margarida Moreira; Queiroz, Margarida João; Baptista, Pedro V.

    2012-05-01

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 ± 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a β-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle-antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  11. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moreira dos Santos, Margarida, E-mail: margarida.santos@fct.unl.pt; Queiroz, Margarida Joao; Baptista, Pedro V. [Universidade Nova de Lisboa, CIGMH, Departamento Ciencias da Vida, Faculdade de Ciencias e Tecnologia (Portugal)

    2012-05-15

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 {+-} 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a {beta}-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle-antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  12. Oxidative stress and toxicity of gold nanoparticles in Mytilus edulis

    Energy Technology Data Exchange (ETDEWEB)

    Tedesco, Sara [Environmental Research Institute of University College Cork, Cork (Ireland); Doyle, Hugh [Tyndall National Institute, Cork (Ireland); Blasco, Julian [Consejo Superior de Investigaciones Cientificas (CSIC), Marine Science Institute of Andalusia, Cadiz (Spain); Redmond, Gareth [Tyndall National Institute, Cork (Ireland); Sheehan, David, E-mail: d.sheehan@ucc.ie [Environmental Research Institute of University College Cork, Cork (Ireland)

    2010-10-15

    Gold nanoparticles (AuNP) have potential applications in drug delivery, cancer diagnosis and therapy, food industry and environment remediation. However, little is known about their potential toxicity or fate in the environment. Mytilus edulis was exposed in tanks to750 ppb AuNP (average diameter 5.3 {+-} 1 nm) for 24 h to study in vivo biological effects of nanoparticles. Traditional biomarkers and an affinity procedure selective for thiol-containing proteins followed by two-dimensional electrophoresis (2DE) separations were used to study toxicity and oxidative stress responses. Results were compared to those obtained for treatment with cadmium chloride, a well known pro-oxidant. M. edulis mainly accumulated AuNP in digestive gland which also showed higher lipid peroxidation. One-dimensional SDS/PAGE (1DE) and 2DE analysis of digestive gland samples revealed decreased thiol-containing proteins for AuNP. Lysosomal membrane stability measured in haemolymph gave lower values for neutral red retention time (NRRT) in both treatments but was greater in AuNP. Oxidative stress occurred within 24 h of AuNP exposure in M. edulis. Previously we showed that larger diameter AuNP caused modest effects, indicating that nanoparticle size is a key factor in biological responses to nanoparticles. This study suggests that M. edulis is a suitable model animal for environmental toxicology studies of nanoparticles.

  13. Synthesis of Gold Nanoparticles Using Whole Cells of Geotrichum candidum

    Directory of Open Access Journals (Sweden)

    Amit Kumar Mittal

    2013-01-01

    Full Text Available The synthesis of nanoparticles with desired size and shape is an important area of research in nanotechnology. Use of biological system is an alternative approach to chemical and physical procedures for the synthesis of metal nanoparticles. An efficient environment-friendly approach for the biosynthesis of rapid and stable Gold nanoparticles (AuNPs using whole cells of Geotrichum candidum is discussed in this paper. The enzymes/proteins present in the microorganism might be responsible for the reduction of metal salts to nanoparticles. Various reaction parameters such as culture age, temperature, pH, metal salt, and cell mass concentrations were optimized. The AuNPs were characterized by UV-visible spectroscopy, dynamic light scattering (DLS, energy dispersive spectroscopy (EDS, scanning electron microscope (SEM, and Fourier transform infrared spectroscopy (FTIR. Nanoparticles were isolated by sonicating the whole cells after treatment with Tween 80. The whole cell mediated process showed the simplistic, feasible, easy to scale up, and low-cost approach for the synthesis of AuNPs.

  14. Gold nanoparticles delivery in mammalian live cells: a critical review.

    Science.gov (United States)

    Lévy, Raphaël; Shaheen, Umbreen; Cesbron, Yann; Sée, Violaine

    2010-01-01

    Functional nanomaterials have recently attracted strong interest from the biology community, not only as potential drug delivery vehicles or diagnostic tools, but also as optical nanomaterials. This is illustrated by the explosion of publications in the field with more than 2,000 publications in the last 2 years (4,000 papers since 2000; from ISI Web of Knowledge, 'nanoparticle and cell' hit). Such a publication boom in this novel interdisciplinary field has resulted in papers of unequal standard, partly because it is challenging to assemble the required expertise in chemistry, physics, and biology in a single team. As an extreme example, several papers published in physical chemistry journals claim intracellular delivery of nanoparticles, but show pictures of cells that are, to the expert biologist, evidently dead (and therefore permeable). To attain proper cellular applications using nanomaterials, it is critical not only to achieve efficient delivery in healthy cells, but also to control the intracellular availability and the fate of the nanomaterial. This is still an open challenge that will only be met by innovative delivery methods combined with rigorous and quantitative characterization of the uptake and the fate of the nanoparticles. This review mainly focuses on gold nanoparticles and discusses the various approaches to nanoparticle delivery, including surface chemical modifications and several methods used to facilitate cellular uptake and endosomal escape. We will also review the main detection methods and how their optimum use can inform about intracellular localization, efficiency of delivery, and integrity of the surface capping.

  15. Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Elavazhagan T

    2011-06-01

    Full Text Available Tamizhamudu Elavazhagan, Kantha D ArunachalamCentre for Interdisciplinary Research, Directorate of Research, SRM University, Kattankulathur-603203, Tamilnadu, IndiaAbstract: 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.Keywords: Memecylon edule, nanoparticles, bioreduction, electron microscopy, FTIR

  16. Highly stable noble metal nanoparticles dispersible in biocompatible solvents: synthesis of cationic phosphonium gold nanoparticles in water and DMSO.

    Science.gov (United States)

    Ju-Nam, Yon; Abdussalam-Mohammed, Wanisa; Ojeda, Jesus J

    2016-01-01

    In this work, we report the synthesis of novel cationic phosphonium gold nanoparticles dispersible in water and dimethyl sulfoxide (DMSO) for their potential use in biomedical applications. All the cationic-functionalising ligands currently reported in the literature are ammonium-based species. Here, the synthesis and characterisation of an alternative system, based on phosphonioalkylthiosulfate zwitterions and phosphonioalkylthioacetate were carried out. We have also demonstrated that our phosphonioalkylthiosulfate zwitterions readily disproportionate into phosphonioalkylthiolates in situ during the synthesis of gold nanoparticles produced by the borohydride reduction of gold(III) salts. The synthesis of the cationic gold nanoparticles using these phosphonium ligands was carried out in water and DMSO. UV-visible spectroscopic and TEM studies have shown that the phosphonioalkylthiolates bind to the surface of gold nanoparticles which are typically around 10 nm in diameter. The resulting cationic-functionalised gold nanoparticles are dispersible in aqueous media and in DMSO, which is the only organic solvent approved by the U.S. Food and Drug Administration (FDA) for drug carrier tests. This indicates their potential future use in biological applications. This work shows the synthesis of a new family of phosphonium-based ligands, which behave as cationic masked thiolate ligands in the functionalisation of gold nanoparticles. These highly stable colloidal cationic phosphonium gold nanoparticles dispersed in water and DMSO can offer a great opportunity for the design of novel biorecognition and drug delivery systems.

  17. Bubble template synthesis of hollow gold nanoparticles and their applications as theranostic agents

    Science.gov (United States)

    Huang, Chienwen

    Hollow gold nanoparticle with a sub-30nm polycrystalline shell and a 50 nm hollow core has been successfully synthesized through the reduction of sodium gold sulfite by electrochemically evolved hydrogen. Such hollow gold nanoparticles exhibit unique plasmonic properties. They strongly scatter and absorb near infrared light. In this thesis we seek to understand the formation mechanism of hollow gold nanoparticles in this new synthesis process and their plasmonic properties. Also, we explore their biomedical applications as theranostic agents (therapeutic and diagnostic imaging). A lithographically patterned electrode consisting of Ag stripes on a glass substrate was used to investigate the formation process of hollow gold nanoparticles. Ag stripes served as working electrode for electrochemically evolution of hydrogen, and adjacent glass areas provided supporting surface for hydrogen nanobubbles nucleation and growth. Hydrogen nanobubbles served as both templates and reducing agents to trigger the autocatalytic disproportionation reaction of sodium gold sulfite. The effects of applied potential and the additives in the electrolyte have been studied. It has been found that the size and size distribution of hollow gold nanoparticle are directly relative to the applied potential, i.e. the hydrogen evolution rate. It has also been found the addition of Ni2+ ions can greatly improve the size distribution of hollow gold nanoparticles that can be contributed to that the newly electrodeposited nickel metal can enhance the hydrogen evolution efficiency. Another additive, ethylenediamine (EDA) can suppress the autocatalytic reaction of gold sulfite to increase the stability of sodium gold sulfite electrolyte. To capture such electrochemically evolved hydrogen nanobubbles, and subsequently to generate hollow gold nanoparticles in large numbers, alumina membranes were placed on the top of the working electrode. Anodic alumina membrane consists of ~200 nm pores, which provides

  18. Unique Gold Nanoparticle Aggregates as a Highly Active SERS Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Schwartzberg, A M; Grant, C D; Wolcott, A; Talley, C E; Huser, T R; Bogomolni, R; Zhang, J Z

    2004-04-06

    A unique gold nanoparticle aggregate (GNA) system has been shown to be an excellent substrate for surface-enhanced Raman scattering (SERS) applications. Rhodamine 6G (R6G), a common molecule used for testing SERS activity on silver, but generally difficult to detect on gold substrates, has been found to readily bind to the GNA and exhibit strong SERS activity due to the unique surface chemistry afforded by sulfur species on the surface. This GNA system has yielded a large SERS enhancement of 10{sup 7}-10{sup 9} in bulk solution for R6G, on par with or greater than any previously reported gold SERS substrate. SERS activity has also been successfully demonstrated for several biological molecules including adenine, L-cysteine, L-lysine, and L-histidine for the first time on a gold SERS substrate, showing the potential of this GNA as a convenient and powerful SERS substrate for biomolecular detection. In addition, SERS spectrum of R6G on single aggregates has been measured. We have shown that the special surface properties of the GNA, in conjunction with strong near IR absorption, make it useful for SERS analysis of a wide variety of molecules.

  19. Mechanistic insights into seeded growth processes of gold nanoparticles

    Science.gov (United States)

    Polte, Jörg; Herder, Martin; Erler, Robert; Rolf, Simone; Fischer, Anna; Würth, Christian; Thünemann, Andreas F.; Kraehnert, Ralph; Emmerling, Franziska

    2010-11-01

    A facile approach for the synthesis of monodisperse gold nanoparticles with radii in the range of 7 to 20 nm is presented. Starting from monodisperse seeds with radii of 7 nm, produced in the first step, the addition of a defined amount of additional precursor material permits distinct size regulation and the realization of predicted nanoparticle sizes. These information were derived from ex- and in situ investigations by comprehensive small angle X-ray scattering (SAXS), X-ray absorption near edge structure (XANES) and UV-Vis data to obtain information on the physicochemical mechanisms. The obtained mechanisms can be transferred to other seeded growth processes. Compared to similar approaches, the presented synthesis route circumvents the use of different reducing or stabilizing agents. The size of resulting nanoparticles can be varied over a large size range presented for the first time without a measurable change in the shape, polydispersity or surface chemistry. Thus, the resulting nanoparticles are ideal candidates for size dependence investigations.A facile approach for the synthesis of monodisperse gold nanoparticles with radii in the range of 7 to 20 nm is presented. Starting from monodisperse seeds with radii of 7 nm, produced in the first step, the addition of a defined amount of additional precursor material permits distinct size regulation and the realization of predicted nanoparticle sizes. These information were derived from ex- and in situ investigations by comprehensive small angle X-ray scattering (SAXS), X-ray absorption near edge structure (XANES) and UV-Vis data to obtain information on the physicochemical mechanisms. The obtained mechanisms can be transferred to other seeded growth processes. Compared to similar approaches, the presented synthesis route circumvents the use of different reducing or stabilizing agents. The size of resulting nanoparticles can be varied over a large size range presented for the first time without a measurable

  20. Anticancer studies of the synthesized gold nanoparticles against MCF 7 breast cancer cell lines

    Science.gov (United States)

    Kamala Priya, M. R.; Iyer, Priya R.

    2015-04-01

    It has been previously stated that gold nanoparticles have been successfully synthesized using various green extracts of plants. The synthesized gold nanoparticles were characterized under scanning electron microscopy and EDX to identify the size of the nanoparticles. It was found that the nanoparticles were around 30 nm in size, which is a commendable nano dimension achieved through a plant mediated synthesis. The nanoparticles were further studied for their various applications. In the current study, we have made attempts to exploit the anticancer ability of the gold nano particles. The nanoparticles were studied against MCF 7 breast cancer cell lines. The results obtained from the studies of anticancer activity showed that gold nanoparticles gave an equivalent good results, in par with the standard drugs against cancer. The AuNP's proved to be efficient even from the minimum concentrations of 2 μg/ml, and as the concentration increased the anticancer efficacy as well increased.

  1. Biosynthesis of gold nanoparticles by Pseudomonas veronii AS41G inhabiting Annona squamosa L.

    Science.gov (United States)

    Baker, Syed; Satish, Sreedharamurthy

    2015-11-05

    Biogenic principles to nanotechnology have generated tremendous attention in recent past owing eco friendly benign process for synthesis of nanoparticles. Present investigation reports extracellular synthesis of gold nanoparticles using cell free supernatant of Pseudomonas veronii AS 41G, a novel endophyte isolated from Annona squamosa L. Gold nanoparticles formation was confirmed with UV-Visible spectrophotometer. FTIR analysis predicted various functional groups responsible for reduction of metal salts and stabilization of gold nanoparticles. Nanoparticles were crystalline in nature as shown in XRD pattern. TEM analysis revealed morphological characteristics of nanoparticles with different size. Thus the present study attributes for facile process for synthesis of gold nanoparticles as an alternative for conventional methods. The study also highlights the new role of novel bacterium Pseudomonas veronii AS41G which will be very valuable as a record for the researchers working on it.

  2. Antibody immobilized cysteamine functionalized-gold nanoparticles for aflatoxin detection

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Aditya; Matharu, Zimple; Sumana, G.; Solanki, Pratima R. [Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, Materials Physics and Engineering Division, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Kim, C.G. [Centre for NanoBioEngineering and Spintronics, Chungnam National University, Daejeon, 305-764 (Korea, Republic of); Malhotra, B.D., E-mail: bansi.malhotra@gmail.co [Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, Materials Physics and Engineering Division, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Centre for NanoBioEngineering and Spintronics, Chungnam National University, Daejeon, 305-764 (Korea, Republic of)

    2010-11-30

    Aflatoxin B{sub 1} antibody (aAFB{sub 1}) covalently attached to cysteamine functionalized-gold nanoparticles (C-AuNP) has been immobilized onto 4-mercaptobenzoic acid (MBA) based self assembled monolayer (SAM) on gold electrode (MBA/Au), for the fabrication of BSA/aAFB{sub 1}-C-AuNP/MBA/Au immunoelectrode. This immunoelectrode has been characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and electrochemical characterization techniques. The electrochemical response studies reveal that the BSA/aAFB{sub 1}-C-AuNP/MBA/Au immunoelectrode can be used to detect AFB{sub 1} in the range of 10-100 ng dL{sup -1} and has sensitivity as 0.45 {mu}A ng{sup -1} dL, limit of detection as 17.90 ng dL{sup -1} and a response time of 60 s.

  3. Preparation of controlled gold nanoparticle aggregates using a dendronization strategy.

    Science.gov (United States)

    Paez, Julieta I; Coronado, Eduardo A; Strumia, Miriam C

    2012-10-15

    In this work, a dendronization strategy was used to control interparticle spacing and the optical properties of gold nanoparticle (NP) aggregates in aqueous media. To achieve this goal, two dendritic disulfides bearing different functionalities on their periphery were synthesized and used as ligands to dendronize gold NPs. The dendronized NPs then undergo aggregation; this process was followed by UV-vis spectroscopy, dynamic light scattering (DLS), and transmission electronic microscopy (TEM) measurements and correlated with Generalized Mie Theory electrodynamics calculations. For comparison, NP functionalization was also studied using a nondendritic ligand. It was found that the use of dendritic disulfides allows for the preparation of controlled NP aggregates. This study demonstrates how different dendronization parameters, such as disulfide concentration, temperature, time and nature of the ligand (dendritic vs nondendritic), determine the control exerted over the size and stability of the NP aggregates. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Complexity of gold nanoparticle formation disclosed by dynamics study

    DEFF Research Database (Denmark)

    Engelbrekt, Christian; Jensen, Palle Skovhus; Sørensen, Karsten

    2013-01-01

    Although chemically synthesized gold nanoparticles (AuNPs) from gold salt (HAuCl4) are among the most studied nanomaterials, understanding the formation mechanisms is a challenge mainly due to limited dynamics information. A range of in situ methods with down to millisecond (ms) time resolution...... have been employed in the present report to monitor time-dependent physical and chemical properties in aqueous solution during the chemical synthesis. Chemical synthesis of AuNPs is a reduction process accompanied by release of ions and protons, and formation of solid particles. Dynamic information......]- to form Au atoms during the early stage of the synthesis process. pH- and conductivity-dynamics point further clearly to formation of coating layers on AuNPs and adsorbate exchange between MES and starch. © 2013 American Chemical Society....

  5. Plasmonic properties of gold nanoparticles can promote neuronal activity

    Science.gov (United States)

    Paviolo, Chiara; Haycock, John W.; Yong, Jiawey; Yu, Aimin; McArthur, Sally L.; Stoddart, Paul R.

    2013-02-01

    As-synthesized, poly(4-styrenesulfonic acid) (PSS)-coated and SiO2 coated gold nanorods were taken up by NG108-15 neuronal cells. Exposure to laser light at the plasmon resonance wavelength of gold nanorods was found to trigger the differentiation process in the nanoparticle treated cells. Results were assessed by measuring the maximum neurite length, the number of neurites per neuron and the percentage of neurons with neurites. When the intracellular Ca2+ signaling was monitored, evidence of photo-generated transients were recorded without altering other normal cell functions. These results open new opportunities for peripheral nerve regeneration treatments and for the process of infrared nerve stimulation.

  6. Preparation of glucose sensors using gold nanoparticles modified diamond electrode

    Science.gov (United States)

    Fachrurrazie; Ivandini, T. A.; Wibowo, W.

    2017-04-01

    A glucose sensor was successfully developed by immobilizing glucose oxidase (GOx) at boron-doped diamond (BDD) electrodes. Prior to GOx immobilization, the BDD was modified with gold nanoparticles (AuNPs). To immobilize AuNPs, the gold surface was modified to nitrogen termination. The characterization of the electrode surface was performed using an X-ray photoelectron spectroscopy and a scanning electron microscope, while the electrochemical properties of the enzyme electrode were characterized using cyclic voltammetry. Cyclic voltammograms of the prepared electrode for D-glucose in phosphate buffer solution pH 7 showed a new reduction peak at +0.16 V. The currents of the peak were linear in the concentration range of 0.1 M to 0.9 M, indicated that the GOx-AuNP-BDD can be applied for electrochemical glucose detection.

  7. Characterization of crystalline dendrimer-stabilized gold nanoparticles

    Science.gov (United States)

    Shi, Xiangyang; Ganser, T. Rose; Sun, Kai; Balogh, Lajos P.; Baker, James R., Jr.

    2006-02-01

    Monodispersed, highly crystalline dendrimer-stabilized gold nanoparticles (Au DSNPs) were synthesized via hydrazine reduction chemistry and stabilized using primary amine-terminated poly(amidoamine) (PAMAM) dendrimers of different generations (generations 2-6) with the same molar ratios of dendrimer terminal nitrogen ligands/gold atoms. The sizes of the synthesized Au DSNPs decrease with the increase of the number of dendrimer generations. These Au DSNPs are fluorescent and display strong blue emission intensity at 458 nm. Polyacrylamide gel electrophoresis (PAGE) analysis indicates that all Au DSNPs are stable and both metal NPs and dendrimer stabilizers do not separate from each other during the electrophoresis process. The synthesized inorganic/organic hybrid Au DSNPs provide new nanoplatforms that will be further modified with various biological ligands for the application of biosensing and targeted cancer therapeutics.

  8. Monitoring of receptor dimerization using plasmonic coupling of gold nanoparticles.

    Science.gov (United States)

    Crow, Matthew J; Seekell, Kevin; Ostrander, Julie H; Wax, Adam

    2011-11-22

    The dimerization of receptors on the cell membrane is an important step in the activation of cell signaling pathways. Several methods exist for observing receptor dimerization, including coimmunoprecipitation, chemical cross-linking, and fluorescence resonance energy transfer (FRET). These techniques are limited in that only FRET is appropriate for live cells, but even that method suffers from photobleaching and bleed-through effects. In this study, we implement an alternative method for the targeting of HER-2 homodimer formation based on the plasmonic coupling of gold nanoparticles functionalized with HER-2 Ab. In the presented studies, SK-BR-3 cells, known to overexpress HER-2, are labeled with these nanoparticles and receptor colocalization is observed using plasmonic coupling. HER-2 targeted nanoparticles bound to these cells exhibit a peak resonance that is significantly red-shifted relative to those bound to similar receptors on A549 cells, which have significantly lower levels of HER-2 expression. This significant red shift indicates plasmonic coupling is occurring and points to a new avenue for assessing dimerization by monitoring their colocalization. To determine that dimerization is occurring, the refractive index of the nanoenvironment of the labels is assessed using a theoretical analysis based on the Mie coated sphere model. The results indicate scattering by single, isolated nanoparticles for the low HER-2 expressing A549 cell line, but the scattering observed for the HER-2 overexpressing SK-BR-3 cell line may only be explained by plasmonic-coupling of proximal nanoparticle pairs. To validate the conformation of nanoparticles bound to HER-2 receptors undergoing dimerization, discrete dipole approximation (DDA) models are used to assess spectra of scattering by coupled nanoparticles. Comparison of the experimental results with theoretical models indicates that NP dimers are formed for the labeling of SK-BR-3 cells, suggesting that receptor

  9. Opto-electronic Properties of Monolayer-Protected Clusters of Au functionalized with a New Fluorescent Ligand

    Science.gov (United States)

    Kountz, Thomas; Thanthirige, Viraj; Reber, Keith; Devadas, Mary Sajini

    Metal nanoclusters are the focus of intense study due to their interesting optical, electronic, and catalytic properties; specifically gold clusters. The applications of gold monolayer-protected clusters (MPCs) are being researched by a series of optical spectroscopic and voltammetric analyses to determine core size, atom-level composition, charge states, and optical/electrical properties. Understanding these fundamental properties is critical for both expansion of applications and creation of new MPCs. The purpose of this study is to expand the applications of gold MPCs, with the attachment of a new coumarin surface ligand - synthesized specifically for this experiment. Our focus in this research is on quantum clusters - specifically Au25(C6S)18. This MPC is researched particularly because of its inherent stability being a magic number cluster. It is created by means of a modified Burst-Schiffrin method. The applications that are influenced include but are not limited to: catalytic activity, solar energy conversion, size-tunable florescence, sensors, and optical electronics.

  10. Anticancer activity of eco-friendly gold nanoparticles against lung and liver cancer cells

    Directory of Open Access Journals (Sweden)

    S. Rajeshkumar

    2016-06-01

    Full Text Available Gold nanoparticles have many applications in biomedical field. Improving delivery of anticancer agents to tumors using nanoparticles is one of the most promising research arenas in the field of nanotechnology. Eco-friendly gold nanoparticles synthesis was studied using marine bacteria Enterococcus sp. The nanoparticle synthesis started at 2 h of incubation time was identified by the formation of ruby red in the reaction mixture and SPR band centered at 545 nm. XRD shows that the strong four intense peaks indicate crystalline nature of nanoparticles. Morphology of nanoparticles analyzed by TEM shows that they are mostly spherical in shape with size ranging from 6 to 13 nm. EDX supports the presence of gold in the synthesized nanoparticles. FTIR reveals the active functional groups in the culture supernatant interaction with gold nanoparticles. As a result synthesized stable gold nanoparticles show more significant anticancer activity against HepG2 and A549 cells at 100 μg concentration of nanoparticles. This synthesis approach is simple, large scaled up a new door for development of targeted anticancer activity using gold nanoparticles and is novel in biomedical applications.

  11. Conveniently assembling dithiocarbamate and gold nanoparticles onto the gold electrode: A new type of electrochemical sensors for biomolecule detection

    Science.gov (United States)

    Li, Maoguo; Gao, Feng; Yang, Ping; Wang, Lun; Fang, Bin

    Dithiocarbamate and gold nanoparticles have been successfully assembled onto the surface of the gold electrode and a novel ultrastable chemical modified electrode (CME) was fabricated conveniently. The as-prepared CME was investigated by electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM) and quartz crystal microbalance (QCM), and its electrochemical behaviors for catalytic oxidation of dopamine (DA) was also observed by cyclic voltammetry (CV) and amperometric i- t curve. The results indicated that the novel surface has endowed the electrode with not only ultrastability but also the advantages of organic ligands and gold nanoparticles, which open up a new way to design high efficient and utility electrochemical sensors for biomolecule detection.

  12. Gold Nanoparticles and Their Alternatives for Radiation Therapy Enhancement

    Directory of Open Access Journals (Sweden)

    Daniel R. Cooper

    2014-10-01

    Full Text Available Radiation therapy is one of the most commonly used treatments for cancer. The dose of delivered ionizing radiation can be amplified by the presence of high-Z materials via an enhancement of the photoelectric effect; the most widely studied material is gold (atomic number 79. However, a large amount is needed to obtain a significant dose enhancement, presenting a challenge for delivery. In order to make this technique of broader applicability, the gold must be targeted, or alternative formulations developed that do not rely solely on the photoelectric effect. One possible approach is to excite scintillating nanoparticles with ionizing radiation, and then exploit energy transfer between these particles and attached dyes in a manner analogous to photodynamic therapy. Doped rare-earth halides and semiconductor quantum dots have been investigated for this purpose. However, although the spectrum of emitted light after radiation excitation is usually similar to that seen with light excitation, the yield is not. Measurement of scintillation yields is challenging, and in many cases has been done only for bulk materials, with little understanding of how the principles translate to the nanoscale. Another alternative is to use local heating using gold or iron, followed by application of ionizing radiation. Hyperthermia pre-sensitizes the tumors, leading to an improved response. Another approach is to use chemotherapeutic drugs that can radiosensitize tumors. Drugs may be attached to high-Z nanoparticles or encapsulated. This article discusses each of these techniques, giving an overview of the current state of nanoparticle-assisted radiation therapy and future directions.

  13. Gold Nanoparticles and Their Alternatives for Radiation Therapy Enhancement

    Science.gov (United States)

    Cooper, Daniel; Bekah, Devesh; Nadeau, Jay

    2014-10-01

    Radiation therapy is one of the most commonly used treatments for cancer. The dose of delivered ionizing radiation can be amplified by the presence of high-Z materials via an enhancement of the photoelectric effect; the most widely studied material is gold (atomic number 79). However, a large amount is needed to obtain a significant dose enhancement, presenting a challenge for delivery. In order to make this technique of broader applicability, the gold must be targeted, or alternative formulations developed that do not rely solely on the photoelectric effect. One possible approach is to excite scintillating nanoparticles with ionizing radiation, and then exploit energy transfer between these particles and attached dyes in a manner analogous to photodynamic therapy. Doped rare-earth halides and semiconductor quantum dots have been investigated for this purpose. However, although the spectrum of emitted light after radiation excitation is usually similar to that seen with light excitation, the yield is not. Measurement of scintillation yields is challenging, and in many cases has been done only for bulk materials, with little understanding of how the principles translate to the nanoscale. Another alternative is to use local heating using gold or iron, followed by application of ionizing radiation. Hyperthermia pre-sensitizes the tumors, leading to an improved response. Another approach is to use chemotherapeutic drugs that can radiosensitize tumors. Drugs may be attached to high-Z nanoparticles or encapsulated. This article discusses each of these techniques, giving an overview of the current state of nanoparticle-assisted radiation therapy and future directions.

  14. Investigation of thiol derivatized gold nanoparticle sensors for gas analysis

    Science.gov (United States)

    Stephens, Jared S.

    Analysis of volatile organic compounds (VOCs) in air and exhaled breath by sensor array is a very useful testing technique. It can provide non-invasive, fast, inexpensive testing for many diseases. Breath analysis has been very successful in identifying cancer and other diseases by using a chemiresistor sensor or array with gold nanoparticles to detect biomarkers. Acetone is a biomarker for diabetes and having a portable testing device could help to monitor diabetic and therapeutic progress. An advantage to this testing method is it is conducted at room temperature instead of 200 degrees Celsius. 3. The objective of this research is to determine the effect of thiol derivatized gold nanoparticles based on sensor(s) detection of VOCs. The VOCs to be tested are acetone, ethanol, and a mixture of acetone and ethanol. Each chip is tested under all three VOCs and three concentration levels (0.1, 1, and 5.0 ppm). VOC samples are used to test the sensors' ability to detect and differentiate VOCs. Sensors (also referred to as a chip) are prepared using several types of thiol derivatized gold nanoparticles. The factors are: thiol compound and molar volume loading of the thiol in synthesis. The average resistance results are used to determine the VOC selectivity of the sensors tested. The results show a trend of increasing resistance as VOC concentration is increased relative to dry air; which is used as baseline for VOCs. Several sensors show a high selectivity to one or more VOCs. Overall the 57 micromoles of 4-methoxy-toluenethiol sensor shows the strongest selectivity for VOCs tested. 3. Gerfen, Kurt. 2012. Detection of Acetone in Air Using Silver Ion Exchanged ZSM-5 and Zinc Oxide Sensing Films. Master of Science thesis, University of Louisville.

  15. Using Glutamic Acid, Phenylalanine and Tryptophan to Synthesize Capped Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kamyar Khoshnevisan

    2011-01-01

    Full Text Available Introduction: The study and investigation of gold nanoparticles produced by amino acid is one of the interesting and applied issues in nanotechnology. In this study, amino acids were used to reduce gold cations as well as an agent to cap gold nanoparticles. In fact, strong bound of amino groups to amino acid and protein on the gold nanoparticles surface indicate the medical applications of these materials. Methods: In this study, gold nanoparticles were prepared and functionalized by using solution reduction containing gold cations with optimum concentration (0.005 M, and also prepared by using glutamic acid, phenylalanine and tryptophan with optimum concentration (0.025 M. Results: The investigation of optimum condition for gold solution and amino acids and also determination of gold nanoparticles were done by UV-Vis. The nanoparticles size were reported 5-20, 10-20 and 20-30 nm respectively by transmission electron microscopy and dynamic light scattering techniques, which is appropriate for biological activities. Conclusion: The comparison of the data from experimental and quantum calculations demonstrated that amino acids have strong band when they are conjugated by anion state. Free carboxylic groups of capped gold nanoparticles with glutamic acid are one of the suitable and capable beads for binding to biological agents.

  16. Analytical performance of molecular beacons on surface immobilized gold nanoparticles of varying size and density.

    Science.gov (United States)

    Uddayasankar, Uvaraj; Krull, Ulrich J

    2013-11-25

    The high quenching efficiency of metal nanoparticles has facilitated its use as quenchers in molecular beacons. To optimize this system, a good understanding of the many factors that influence molecular beacon performance is required. In this study, molecular beacon performance was evaluated as a function of gold nanoparticle size and its immobilization characteristics. Gold nanoparticles of 4 nm, 15 nm and 87 nm diameter, were immobilized onto glass slides. Each size regime offered distinctive optical properties for fluorescence quenching of molecular dyes that were conjugated to oligonucleotides that were immobilized to the gold nanoparticles. Rigid double stranded DNA was used as a model to place fluorophores at different distances from the gold nanoparticles. The effect of particle size and also the immobilization density of nanoparticles was evaluated. The 4 nm and 87 nm gold nanoparticles offered the highest sensitivity in terms of the change in fluorescence intensity as a function of distance (3-fold improvement for Cy5). The optical properties of the molecular fluorophore was of significance, with Cy5 offering higher contrast ratios than Cy3 due to the red-shifted emission spectrum relative to the plasmon peak. A high density of gold nanoparticles reduced contrast ratios, indicating preference for a monolayer of immobilized nanoparticles when considering analytical performance. Molecular beacon probes were then used in place of the double stranded oligonucleotides. There was a strong dependence of molecular beacon performance on the length of a linker used for attachment to the nanoparticle surface. The optimal optical performance was obtained with 4 nm gold nanoparticles that were immobilized as monolayers of low density (5.7×10(11)particles cm(-2)) on glass surfaces. These nanoparticle surfaces offered a 2-fold improvement in analytical performance of the molecular beacons when compared to other nanoparticle sizes investigated. The principles developed

  17. Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles

    Science.gov (United States)

    Elavazhagan, Tamizhamudu; Arunachalam, Kantha D

    2011-01-01

    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. PMID:21753878

  18. Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles.

    Science.gov (United States)

    Elavazhagan, Tamizhamudu; Arunachalam, Kantha D

    2011-01-01

    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.

  19. Quantitative surface acoustic wave detection based on colloidal gold nanoparticles and their bioconjugates.

    Science.gov (United States)

    Chiu, Chi-Shun; Gwo, Shangjr

    2008-05-01

    The immobilization scheme of monodispersed gold nanoparticles (10-nm diameter) on piezoelectric substrate surfaces using organosilane molecules as cross-linkers has been developed for lithium niobate (LiNbO3) and silicon oxide (SiO2)/gold-covered lithium tantalate (LiTaO3) of Rayleigh and guided shear horizontal- (guided SH) surface acoustic wave (SAW) sensors. In this study, comparative measurements of gold nanoparticle adsorption kinetics using high-resolution field-emission scanning electron microscopy and SAW sensors allow the frequency responses of SAW sensors to be quantitatively correlated with surface densities of adsorbed nanoparticles. Using this approach, gold nanoparticles are used as the "nanosized mass standards" to scale the mass loading in a wide dynamical range. Rayleigh-SAW and guided SH-SAW sensors are employed here to monitor the surface mass changes on the device surfaces in gas and liquid phases, respectively. The mass sensitivity ( approximately 20 Hz.cm2/ng) of Rayleigh-SAW device (fundamental oscillation frequency of 113.3 MHz in air) is more than 2 orders of magnitude higher than that of conventional 9-MHz quartz crystal microbalance sensors. Furthermore, in situ (aqueous solutions), real-time measurements of adsorption kinetics for both citrate-stabilized gold nanoparticles and DNA-gold nanoparticle conjugates are also demonstrated by guided SH-SAW (fundamental oscillation frequency of 121.3 MHz). By comparing frequency shifts between the adsorption cases of gold nanoparticles and DNA-gold nanoparticle conjugates, the average number of bound oligonucleotides per gold nanoparticle can also be determined. The high mass sensitivity ( approximately 6 Hz.cm2/ng) of guided SH-SAW sensors and successful detection of DNA-gold nanoparticle conjugates paves the way for real-time biosensing in liquids using nanoparticle-enhanced SAW devices.

  20. Gold nanoparticle-based fluorescent sensor for the analysis of dithiocarbamate pesticides in water

    DEFF Research Database (Denmark)

    Senkbeil, Silja; Lafleur, Josiane P.; Jensen, Thomas G.

    2012-01-01

    and environmental health. This paper demonstrates the potential of a gold nanoparticle-based microfluidic sensor for in field detection of dithiocarbamate pesticides at remote locations. Combining the attractive optical properties of gold nanoparticles with on chip mixing and detection, using a simple digital...... camera, a detection limit of 16 μg L-1 for Ziram, a dithiocarbamate pesticide, was obtained....

  1. Gold nanoparticle-based fluorescent sensor for the analysis of dithiocarbamate pesticides in water

    DEFF Research Database (Denmark)

    Senkbeil, Silja; Lafleur, Josiane P.; Jensen, Thomas Glasdam;

    2012-01-01

    and environmental health. This paper demonstrates the potential of a gold nanoparticle-based microfluidic sensor for in field detection of dithiocarbamate pesticides at remote locations. Combining the attractive optical properties of gold nanoparticles with on chip mixing and detection, using a simple digital...... camera, a detection limit of 16 μg L-1 for Ziram, a dithiocarbamate pesticide, was obtained....

  2. Anti-metastatic activity of biologically synthesized gold nanoparticles on human fibrosarcoma cell line HT-1080.

    Science.gov (United States)

    Karuppaiya, Palaniyandi; Satheeshkumar, Elumalai; Chao, Wei-Ting; Kao, Lin-Yi; Chen, Emily Chin-Fun; Tsay, Hsin-Sheng

    2013-10-01

    Plants are exploited as a potential source for the large-scale production of noble gold nanoparticles in the recent years owing to their various potential applications in nanobiotechnology and nanomedicine. The present work describes green biosynthetic procedures for the production of gold nanoparticles for the first time by using an aqueous extract of the Dysosma pleiantha rhizome. The biosynthesized gold nanoparticles were confirmed and characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy equipped with energy dispersive spectroscopy. The results revealed that aqueous extract of D. pleiantha rhizome has potential to reduce chloroauric ions into gold nanoparticles and the synthesized gold nanoparticles were showed spherical in shape with an average of 127nm. Further, we investigated the anti-metastatic activity of biosynthesized gold nanoparticles against human fibrosarcoma cancer cell line HT-1080. The results showed that the biosynthesized gold nanoparticles were non-toxic to cell proliferation and, also it can inhibit the chemo-attractant cell migration of human fibrosarcoma cancer cell line HT-1080 by interfering the actin polymerization pathway. Thus, the usage of gold nanoparticles biosynthesized from D. pleiantha rhizome can be used as a potential candidate in the drug and gene delivery to metastatic cancer.

  3. Effect on nerve structures of functionalized gold-chitosan nanoparticles obtained by one pot synthesis

    Directory of Open Access Journals (Sweden)

    Marius Dobromir

    2011-02-01

    Full Text Available Gold nanoparticles have potential applications in drug delivery, cancer diagnosis and therapy, food industry and environment remediation. However, little is known about their potential toxicity or fate in the environment. In this study we observed significant effects of functionalized gold-chitosan nanoparticles obtained by one pot synthesis on nerve structures of Wistar rats.

  4. Gold-plated silver nanoparticles engineered for sensitive plasmonic detection amplified by morphological changes.

    Science.gov (United States)

    Hobbs, Krysten; Cathcart, Nicole; Kitaev, Vladimir

    2016-07-28

    Gold-plated silver nanoparticles have been developed to undergo morphological changes that enhance the surface plasmon resonance (SPR) sensing response. These morphological changes were realized through thin-frame gold plating that both reinforces the nanoparticle edges and enables partial silver etching upon exposure to several biological molecules, including thiols and amines.

  5. A facile electrochemical route to the preparation of uniform and monoatomic copper shells for gold nanoparticles.

    Science.gov (United States)

    Gründer, Y; Ramasse, Q M; Dryfe, R A W

    2015-02-28

    Copper on gold forms a monolayer deposit via underpotential deposition. For gold particles adsorbed at a liquid-liquid interface this results in a uniform one monolayer thick shell. This approach offers a new route for the uniform functionalisation of nanoparticles and presents a way to probe fundamental processes that underlie nanoparticle synthesis.

  6. Physically-synthesized gold nanoparticles containing multiple nanopores for enhanced photothermal conversion and photoacoustic imaging.

    Science.gov (United States)

    Park, Jisoo; Kang, Heesung; Kim, Young Heon; Lee, Sang-Won; Lee, Tae Geol; Wi, Jung-Sub

    2016-08-25

    Physically-synthesized gold nanoparticles having a narrow size distribution and containing multiple nanopores have been utilized as photothermal converters and imaging contrast agents. Nanopores within the gold nanoparticles make it possible to increase the light-absorption cross-section and consequently exhibit distinct improvements in photothermal conversion and photoacoustic imaging efficiencies.

  7. Gold nanostars as thermoplasmonic nanoparticles for optical heating.

    Science.gov (United States)

    Rodríguez-Oliveros, R; Sánchez-Gil, José A

    2012-01-02

    Gold nanostars are theoretically studied as efficient thermal heaters at their corresponding localized surface-plasmon resonances (LSPRs). Numerical calculations are performed through the 3D Green's Theorem method to obtain the absorption and scattering cross sections for Au nanoparticles with star-like shape of varying symmetry and tip number. Their unique thermoplasmonic properties, with regard to their (red-shifted) LSPR wavelentgh, (∼ 30-fold increase) steady-state temperature, and scattering/absorption cross section ratios, make them specially suitable for optical heating and in turn for cancer thermal therapy.

  8. Photoacoustic emission from fluorescent nanodiamonds enhanced with gold nanoparticles.

    Science.gov (United States)

    Zhang, Bailin; Fang, Chia-Yi; Chang, Cheng-Chun; Peterson, Ralph; Maswadi, Saher; Glickman, Randolph D; Chang, Huan-Cheng; Ye, Jing Yong

    2012-07-01

    Fluorescent nanodiamonds (FNDs) have drawn much attention in recent years for biomedical imaging applications due to their desired physical properties including excellent photostability, high biocompatibility, extended far-red fluorescence emission, and ease of surface functionalization. Here we explore a new feature of FNDs, i.e. their photoacoustic emission capability, which may lead to potential applications of using FNDs as a dual imaging contrast agent for combined fluorescence and photoacoustic imaging modalities. We observed significant enhancement of photoacoustic emission from FNDs when they were conjugated with gold nanoparticles (GNPs).

  9. Gold nanoparticle-decellularized matrix hybrids for cardiac tissue engineering.

    Science.gov (United States)

    Shevach, Michal; Fleischer, Sharon; Shapira, Assaf; Dvir, Tal

    2014-10-01

    Decellularized matrices are valuable scaffolds for engineering functional cardiac patches for treating myocardial infarction. However, the lack of quick and efficient electrical coupling between adjacent cells may jeopardize the success of the treatment. To address this issue, we have deposited gold nanoparticles on fibrous decellularized omental matrices and investigated their morphology, conductivity, and degradation. We have shown that cardiac cells engineered within the hybrid scaffolds exhibited elongated and aligned morphology, massive striation, and organized connexin 43 electrical coupling proteins. Finally, we have shown that the hybrid patches demonstrated superior function as compared to pristine patches, including a stronger contraction force, lower excitation threshold, and faster calcium transients.

  10. Optical Properties of Gold Nanoparticle Assemblies on a Glass Surface

    Science.gov (United States)

    Stetsenko, M. O.; Rudenko, S. P.; Maksimenko, L. S.; Serdega, B. K.; Pluchery, O.; Snegir, S. V.

    2017-05-01

    The assemblies of cross-linked gold nanoparticles (AuNP) attract lot of scientific attention due to feasible perspectives of their use for development of scaled contact electrodes. Here, we developed and tested method of solid-state formation of dimers created from small AuNP ( 18 nm) cross-linked with 1.9-nonadithiol (NDT) molecules. The morphology of created coating of a glass surface and its optical-polarization properties have been studied in detail by combination of scanning electron microscopy, atomic force microscopy, UV-visible spectroscopy, and modulation-polarization spectroscopy.

  11. PXRF characterization of gold nanoparticles in human cancer cell

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Fabio; Estevam, Marcelo; Appoloni, Carlos R.; Panis, Carolina; Galvao, Tiago Dutra [Universidade Estadual de Londrina (UEL), PR (Brazil); Zucolotto, Valtencir [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Inst. de Fisica

    2011-07-01

    Full Text: Nanomaterials, including nanoparticles and nanotubes, have been widely used in biotechnology and medicine. Applications include systems for controlled release of drugs, biomarkers, biosensors and devices for diagnosis of various diseases like cancer, tuberculosis and Chagas. In the case of cancer, the success of current anti-cancer therapy depends on the speed of diagnosis. Gold nanoparticles can be used to visualize lesions or to destroy cancer cells. In this study, was developed a methodology for identification and quantification of gold nanoparticles (AuNPs) deposited on polymer films and matrices that simulate the human skin with pH 7.4, as well as determining the radiation dose of the measures. The nanoparticles were chemically synthesized at the Laboratory of Nanomedicine and nanotoxicology the IFSC/USP and used in concentrations from 1 ppm to 1000 ppm. The measurements were performed with the portable system of the Laboratory of Applied Nuclear Physics (LFNA-UEL), composed of X-ray detector type S-PIN with a resolution of 149 eV for the line at 5.9 keV Mn (AMPTEK) and an X-ray detector type Si-Drift with a resolution of 139 eV for 5.9 keV line of Fe (AMPTEK) and standard electronics, the excitation of samples was performed with a mini X-ray tube with target Silver operated at 28 kV and 10{mu} A (MOXTEK). Filters were used for silver and aluminum in the output of X-ray tube. The positioner for the set of excitation-detection allows degrees of freedom of translation and rotation. The lower limit of quantification was 5 ppm of gold, using measurement times of 300 s to 1000 s, with R2 ranging from 0.92 to 0.96. X-ray fluorescence lines of gold were analyzed by 8.5 keV, 9.7 keV and 11.4 keV showing a statistical deviation of 0.24. (author)

  12. Optical nanoprobes based on gold nanoparticles for sugar sensing.

    Science.gov (United States)

    Scampicchio, Matteo; Arecchi, Alessandra; Mannino, Saverio

    2009-04-01

    A novel optical nanoprobe for sugar sensing is reported. The assay used an electrospun polyamide mesh containing Au salts. The reaction of carbohydrates with these Au salts in alkaline media generates gold nanoparticles (AuNPs) at room temperature without the need for Au seeds. The optical properties of the resulting AuNPs relate to the total reducing sugar content of the samples analysed. The development of such inexpensive disposable optical nanoprobes could find applications in a host of industrial, biomedical and clinical fields.

  13. Capping and in vivo toxicity studies of gold nanoparticles

    Science.gov (United States)

    Nghiem, Thi Ha Lien; Tuyen Nguyen, Thi; Fort, Emmanuel; Phuong Nguyen, Thanh; Nhung Hoang, Thi My; Quy Nguyen, Thi; Nhung Tran, Hong

    2012-03-01

    Water-dispersed colloidal gold nanoparticles (AuNPs) with high concentration were synthesized from metal precursor HAuCl4. The bovine serum albumin (BSA) and heterobiofunctionalized thiol polyethylene glycol acid (HS-PEG-COOH) were used as biofunctionalized layers for the synthesized AuNPs. The BSA and HS-PEG-COOH bound to the AuNPs were characterized qualitatively and quantitatively by transmission electron microscope and UV-VS spectrophotometer. The fabricated BSA and HS-PEG-COOH-capped AuNPs were introduced in mouse to study its toxicity and its availability in the liver.

  14. Mitochondria as a target for radiosensitisation by gold nanoparticles

    Science.gov (United States)

    McMahon, S. J.; McNamara, A. L.; Schuemann, J.; Prise, K. M.; Paganetti, H.

    2017-01-01

    While Gold Nanoparticles (GNPs) have been extensively studied as radiosensitisers in recent years, there is a lack of studies of their impact on targets outside of the cell’s nuclear DNA. We present Monte Carlo simulations of the energy deposited by X-ray irradiation in mitochondria in cells with and without cytoplasmic GNPs. These simulations show that the presence of GNPs within the cytoplasm can significantly increase (3-4 fold) the number of ionisation clusters of both small and large sizes. As these clusters are strongly associated with DNA damage, these results suggest that mitochondrial DNA may be a significant target for GNP radiosensitisation when the nanoparticles cannot penetrate the cell nucleus.

  15. Gold Nanoparticles and Microwave Irradiation Inhibit Beta-Amyloid Amyloidogenesis

    Directory of Open Access Journals (Sweden)

    Bastus Neus

    2008-01-01

    Full Text Available Abstract Peptide-Gold nanoparticles selectively attached to β-amyloid protein (Aβ amyloidogenic aggregates were irradiated with microwave. This treatment produces dramatic effects on the Aβ aggregates, inhibiting both the amyloidogenesis and the restoration of the amyloidogenic potential. This novel approach offers a new strategy to inhibit, locally and remotely, the amyloidogenic process, which could have application in Alzheimer’s disease therapy. We have studied the irradiation effect on the amyloidogenic process in the presence of conjugates peptide-nanoparticle by transmission electronic microscopy observations and by Thioflavine T assays to quantify the amount of fibrils in suspension. The amyloidogenic aggregates rather than the amyloid fibrils seem to be better targets for the treatment of the disease. Our results could contribute to the development of a new therapeutic strategy to inhibit the amyloidogenic process in Alzheimer’s disease.

  16. Uniform Decoration of Reduced Graphene Oxide Sheets with Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Huanping Yang

    2012-01-01

    Full Text Available A simple method employing ionic liquid functionalization is developed to achieve the uniform decoration of reduced graphene oxide sheets with gold nanoparticles. The synthesis of ionic liquid modified graphene oxide is accomplished by covalently binding 1-(3-Aminopropyl imidazole with GO sheets. The formation mechanism of Au nanoparticles on RGO sheets is proposed to load AuCl4- onto the surface of GO sheets through anion exchange; then reduce AuCl4- to Au NPs and at the same time reduce GO sheets to RGO sheets via a one-step process. The presence of Au NPs is well identified by SEM, TEM, and XPS. As a concept, the RGO-supported Au NPs is applied to surface-enhanced Raman spectroscopy.

  17. Gold nanoparticles in columnar matrix of discotic liquid crystal

    Science.gov (United States)

    Supreet, Kumar, Rishi; Pratibha, R.; Kumar, Sandeep; Raina, K. K.

    2013-06-01

    Hexanethiolate-stabilized gold nanoparticles (GNP) were synthesized by the method adopted by Song et al.[2]. Average size of GNPs was determined by scanning transmission electron microscopy (STEM). This method yielded nanoparticles with average particle size of 1.5 nm. In the present work, we have incorporated GNPs in columnar matrix of discotic liquid crystal. The thermo-physical properties of these mixtures were investigated using polarizing optical micrography (POM), differential scanning calorimetry (DSC) and dielectric spectroscopy. Results show GNPs does not affect the hexagonal arrangement of columns of DLC. However, there is decrease in mesophase to crystallization temperature as confirmed by DSC. This approach of crossing of the field of nanotechnology with DLC may lead to novel materials with interesting properties that are useful for many device applications.

  18. The Deposition of Gold Nanoparticles Onto Activated Carbon

    Directory of Open Access Journals (Sweden)

    Jaworski W.

    2014-10-01

    Full Text Available This work reports the results of spectrophotometric, dynamic light scattering (DLS and microscopic (SEM studies of the gold nanoparticles (AuNPs deposition on activated carbon (AC surface modified with primary (ethanolamine and secondary (diethylenetriamine and triethylenetetramine amines. It was found that this method is efficient for deposition of AuNPs from aqueous solution. However, nanoparticles change their morphology depending on the kind of amine used in experiments. On the AC surface modified with ethanolamine, the uniform spherical AuNPs were formed. In case of diethylenetriamine and triethylenetetramine application, the agglomerates of AuNPs are present. The diameter of individual AuNPs did not exceed 15 nm and was bigger as compared with the diameter of particles present in precursor solution (ca. 10 nm.

  19. Antibacterial gold nanoparticles-biomass assisted synthesis and characterization.

    Science.gov (United States)

    Badwaik, Vivek D; Willis, Chad B; Pender, Dillon S; Paripelly, Rammohan; Shah, Monic; Kherde, Yogesh A; Vangala, Lakshmisri M; Gonzalez, Matthew S; Dakshinamurthy, Rajalingam

    2013-10-01

    Xylose is a natural monosaccharide found in biomass such as straw, pecan shells, cottonseed hulls, and corncobs. Using this monosaccharide, we report the facile, green synthesis and characterization of stable xylose encapsulated gold nanoparticles (Xyl-GNPs) with potent antibacterial activity. Xyl-GNPs were synthesized using the reduction property of xylose in an aqueous solution containing choloraurate anions carried out at room temperature and atmospheric pressure. These nanoparticles were stable and near spherical in shape with an average diameter of 15 +/- 5 nm. Microbiological assay results showed the concentration dependent antibacterial activity of these particles against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus epidermidis) bacteria. Thus the facile, environmentally friendly Xyl-GNPs have many potential applications in chemical and biomedical industries, particularly in the development of antibacterial agents in the field of biomedicine.

  20. Gold-manganese nanoparticles for targeted diagnostic and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Murph, Simona Hunyadi [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-11-10

    Imagine the possibility of non-invasive, non-radiation based Magnetic resonance imaging (MRI) in combating cardiac disease. Researchers at the Savannah River National Laboratory (SRNL) are developing a process that would use nanotechnology in a novel, targeted approach that would allow MRIs to be more descriptive and brighter, and to target specific organs. Researchers at SRNL have discovered a way to use multifunctional metallic gold-manganese nanoparticles to create a unique, targeted positive contrast agent. SRNL Senior Scientist Dr. Simona Hunyadi Murph says she first thought of using the nanoparticles for cardiac disease applications after learning that people who survive an infarct exhibit up to 15 times higher rate of developing chronic heart failure, arrhythmias and/or sudden death compared to the general population. Without question, nanotechnology will revolutionize the future of technology. The development of functional nanomaterials with multi-detection modalities opens up new avenues for creating multi-purpose technologies for biomedical applications.

  1. Biosynthesis of anisotropic gold nanoparticles using Maduca longifolia extract and their potential in infrared absorption.

    Science.gov (United States)

    Fayaz, A Mohammed; Girilal, M; Venkatesan, R; Kalaichelvan, P T

    2011-11-01

    Metal nanoparticles, in general, and gold nanoparticles, in particular, are very attractive because of their size- and shape-dependent properties. Biosynthesis of anisotropic gold nanoparticles using aqueous extract of Madhuca longifolia and their potential as IR blockers has been demonstrated. The tyrosine residue was identified as the active functional group for gold ion reduction. These gold nanoparticles were characterized by of UV-Vis spectrophotometer, FTIR, TEM and HrTEM. The presence of proteins was identified by FTIR, SDS-PAGE, UV-Vis and fluorescence spectroscopy. The micrograph revealed the formation of anisotropic gold nanoaprticles. The biologically synthesized gold nanotriangles can be easily coated in the glass windows which are highly efficient in absorbing IR radiations.

  2. Use of Soybean Lecithin in Shape Controlled Synthesis of Gold Nanoparticles

    Science.gov (United States)

    Ayres, Benjamin Robert

    The work presented in this dissertation is a composite of experiments in the growth of gold nanoparticles with specific optical properties of interest. The goal is to synthesize these gold nanoparticles using soybean extract for not only shape control, but for propensity as a biocompatible delivery system. The optical properties of these nanoparticles has found great application in coloring glass during the Roman empire and, over the centuries, has grown into its own research field in applications of nanoparticulate materials. Many of the current functions include use in biological systems as biosensors and therapeutic applications, thus making biocompatibility a necessity. Current use of cetyltrimethylammonium bromide leads to rod-shaped gold nanoparticles, however, the stability of these gold nanoparticles does not endure for extended periods of time in aqueous media. In my research, two important components were found to be necessary for stable, anisotropic growth of gold nanoparticles. In the first experiments, it was found that bromide played a key role in shape control. Bromide exchange on the gold atoms led to specific packing of the growing crystals, allowing for two-dimensional growth of gold nanoparticles. It was also discerned that soybean lecithin contained ligands that blocked specific gold facets leading to prismatic gold nanoparticle growth. These gold nanoprisms give a near infrared plasmon absorption similar to that of rod-shaped gold nanoparticles. These gold nanoprisms are discovered to be extremely stable in aqueous media and remain soluble for extended periods of time, far longer than that of gold nanoparticles grown using cetyltrimethylammonium bromide. Since soy lecithin has a plethora of compounds present, it became necessary to discover which compound was responsible for the shape control of the gold nanoprisms in order to optimize the synthesis and allow for a maximum yield of the gold nanoprisms. Many of these components were identified

  3. Functionalized self-assembly of gold nanoparticles functionalized with amino acids and aleurone globular protein

    Science.gov (United States)

    Tomoaia-Cotisel, Maria; Mocanu, Aurora; Horovitz, Ossi; Indrea, Emil; Tomoaia, Gheorghe; Bratu, Ioan

    2009-01-01

    Gold colloidal aqueous solutions were synthesized and characterized by UV-Vis spectroscopy and TEM. Gold films were prepared on silanized glass slides at room temperature and with thermal treatment. The interaction of gold nanoparticles with biomolecules (amino acids, protein) was studied using UV-Vis spectroscopy, AFM, TEM and X-ray diffraction.

  4. Assessment of the In Vivo Toxicity of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Liau Ian

    2009-01-01

    Full Text Available Abstract The environmental impact of nanoparticles is evident; however, their toxicity due to their nanosize is rarely discussed. Gold nanoparticles (GNPs may serve as a promising model to address the size-dependent biological response to nanoparticles because they show good biocompatibility and their size can be controlled with great precision during their chemical synthesis. Naked GNPs ranging from 3 to 100 nm were injected intraperitoneally into BALB/C mice at a dose of 8 mg/kg/week. GNPs of 3, 5, 50, and 100 nm did not show harmful effects; however, GNPs ranging from 8 to 37 nm induced severe sickness in mice. Mice injected with GNPs in this range showed fatigue, loss of appetite, change of fur color, and weight loss. Starting from day 14, mice in this group exhibited a camel-like back and crooked spine. The majority of mice in these groups died within 21 days. Injection of 5 and 3 nm GNPs, however, did not induce sickness or lethality in mice. Pathological examination of the major organs of the mice in the diseased groups indicated an increase of Kupffer cells in the liver, loss of structural integrity in the lungs, and diffusion of white pulp in the spleen. The pathological abnormality was associated with the presence of gold particles at the diseased sites, which were verified by ex vivo Coherent anti-Stoke Raman scattering microscopy. Modifying the surface of the GNPs by incorporating immunogenic peptides ameliorated their toxicity. This reduction in the toxicity is associated with an increase in the ability to induce antibody response. The toxicity of GNPs may be a fundamental determinant of the environmental toxicity of nanoparticles.

  5. Assessment of the In Vivo Toxicity of Gold Nanoparticles

    Science.gov (United States)

    Chen, Yu-Shiun; Hung, Yao-Ching; Liau, Ian; Huang, G. Steve

    2009-08-01

    The environmental impact of nanoparticles is evident; however, their toxicity due to their nanosize is rarely discussed. Gold nanoparticles (GNPs) may serve as a promising model to address the size-dependent biological response to nanoparticles because they show good biocompatibility and their size can be controlled with great precision during their chemical synthesis. Naked GNPs ranging from 3 to 100 nm were injected intraperitoneally into BALB/C mice at a dose of 8 mg/kg/week. GNPs of 3, 5, 50, and 100 nm did not show harmful effects; however, GNPs ranging from 8 to 37 nm induced severe sickness in mice. Mice injected with GNPs in this range showed fatigue, loss of appetite, change of fur color, and weight loss. Starting from day 14, mice in this group exhibited a camel-like back and crooked spine. The majority of mice in these groups died within 21 days. Injection of 5 and 3 nm GNPs, however, did not induce sickness or lethality in mice. Pathological examination of the major organs of the mice in the diseased groups indicated an increase of Kupffer cells in the liver, loss of structural integrity in the lungs, and diffusion of white pulp in the spleen. The pathological abnormality was associated with the presence of gold particles at the diseased sites, which were verified by ex vivo Coherent anti-Stoke Raman scattering microscopy. Modifying the surface of the GNPs by incorporating immunogenic peptides ameliorated their toxicity. This reduction in the toxicity is associated with an increase in the ability to induce antibody response. The toxicity of GNPs may be a fundamental determinant of the environmental toxicity of nanoparticles.

  6. Photocatalytic and antibacterial response of biosynthesized gold nanoparticles.

    Science.gov (United States)

    Khan, Arif Ullah; Yuan, Qipeng; Wei, Yun; Khan, Gul Majid; Khan, Zia Ul Haq; Khan, Shafiullah; Ali, Farman; Tahir, Kamran; Ahmad, Aftab; Khan, Faheem Ullah

    2016-09-01

    Increase in the bacterial resistance to available antibiotics and water contamination by different toxic organic dyes are both severe problems throughout the world. To overcome these concerns, new methodologies including synthesis of nontoxic, human friendly and efficient nanoparticles is required. These nanoparticles not even inhibit the growth of microorganisms but are also effective in the degradation of toxic organics in waste water thus providing a clean and human friendly environment. The use of plants extracts to synthesize and stabilize noble metal nanoparticles have been considered as safe, cost-effective, eco-benign and green approach nowadays. In the present study, Longan fruit juice proficiently reduced ionic gold (Au(+3)) to gold nanoparticles (AuNPs) as well as mediated the stabilization of AuNPs. The antibacterial activity of AuNPs was carried out against both gram positive and gram negative bacteria using agar well diffusion method, followed by the determination of Minimum inhibitory concentration (MIC) values. AuNPs were found to have significant antibacterial activity against Escherichia coli with MIC values of 75μg/ml while outstanding MIC values of 50μg/ml against Staphylococcus areous and Basilus subtilus. AuNPs revealed significant photocatalytic degradation (76%) of methylene blue in time period of 55min, indicating the effective photocatalytic property of biosynthesized AuNPs (K=0.29/min, r(2)=0.95). The considerable antibacterial and photocatalytic activities of the photosynthesized AuNPs can be attributed towards their small size, spherical morphology and uniform dispersion. Our finding suggests the possible therapeutic potential of biogenic AuNPs in the development of new antibacterial agents as well as in the development of effective photocatalysts.

  7. Assembly of citrate gold nanoparticles on hydrophilic monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Vikholm-Lundin, Inger, E-mail: inger.vikholm-lundin@uta.fi [University of Tampere, BioMediTech, Tampere (Finland); Fimlab Laboratories Ltd., Tampere (Finland); Rosqvist, Emil; Ihalainen, Petri [Abo Akademi University, Center for Functional Materials, Laboratory of Physical Chemistry (Finland); Munter, Tony [VTT Technical Research Centre of Finland, Process Chemistry end Environmental Engineering, Tampere (Finland); Honkimaa, Anni [University of Tampere, Department of Virology, School of Medicine, Tampere (Finland); Marjomäki, Varpu [University of Jyväskylä, Department of Biological and Environmental Science, Nanoscience Center, Jyväskylä (Finland); Albers, Willem M. [BioNavis Oy Ltd., Ylöjärvi, Tampere (Finland); Peltonen, Jouko [Abo Akademi University, Center for Functional Materials, Laboratory of Physical Chemistry (Finland)

    2016-08-15

    Highlights: • The self-assembled layers were all hydrophilic with Lipa-pTHMMAA exhibiting close to full wetting. • The polyacrylamide layers smoothen the gold surface to a higher extent than the polyethylene glycol and lipoic acid terminated with an amino group. • SPR resonance curves shift to higher angles and become increasingly damped when large nanoparticles assembled on the surface. • Topographical images confirmed that the highest number of particles were assembled on the polyethylene glycol monolayer. • By increasing the interaction time more particles could be assembled on the surface. - Abstract: Self-assembled monolayers (SAMs) as model surfaces were linked onto planar gold films thorough lipoic acid or disulfide groups. The molecules used were polyethylene glycol (EG-S-S), N-[tris-(hydroxymethyl)methyl]acrylamide polymers with and without lipoic acid (Lipa-pTHMMAA and pTHMMAA) and a lipoic acid triazine derivative (Lipa-MF). All the layers, but Lipa-MF with a primary amino group were hydroxyl terminated. The layers were characterized by contact angle measurements and atomic force microscopy, AFM. Citrate stabilized nanoparticles, AuNPs in water and phosphate buffer were allowed to assemble on the layers for 10 min and the binding was followed in real-time with surface plasmon resonance, SPR. The SPR resonance curves were observed to shift to higher angles and become increasingly damped, while also the peaks strongly broaden when large nanoparticles assembled on the surface. Both the angular shift and the damping of the curve was largest for nanoparticles assembling on the EG-S-S monolayer. High amounts of particles were also assembled on the pTHMMAA layer without the lipoic acid group, but the damping of the curve was considerably lower with a more even distribution of the particles. Topographical images confirmed that the highest number of particles were assembled on the polyethylene glycol monolayer. By increasing the interaction time more

  8. Impedance Analysis of Colloidal Gold Nanoparticles in Chromatography Paper for Quantitation of an Immunochromatographic Assay.

    Science.gov (United States)

    Hori, Fumitaka; Harada, Yuji; Kuretake, Tatsumi; Uno, Shigeyasu

    2016-01-01

    A detection method of gold nanoparticles in chromatography paper has been developed for a simple, cost-effective and reliable quantitation of immunochromatographic strip test. The time courses of the solution resistance in chromatography paper with the gold nanoparticles solution are electrochemically measured by chrono-impedimetry. The dependence of the solution resistance on the concentration of gold nanoparticles has been successfully observed. The main factor to increase the solution resistance may be obstruction of the ion transport due to the presence of gold nanoparticles. The existence of gold nanoparticles with 1.92 × 10(9) particles/mL in an indistinctly-colored chromatography paper is also identified by a solution resistance measurement. This indicates that the solution resistance assay has the potential to lower the detection limit of the conventional qualitative assay.

  9. Semi-quantitative determination of cationic surfactants in aqueous solutions using gold nanoparticles as reporter probes.

    Science.gov (United States)

    Kuong, Chi-Lap; Chen, Wei-Yu; Chen, Yu-Chie

    2007-03-01

    Concentrations of cationic surfactants in aqueous solutions have been estimated on the basis of changes in the color of gold nanoparticles, used as reporter probes. We have shown that the colors of gold nanoparticles with anionic protective groups on their surfaces shift from red to indigo/purple and then back to red in a range of cationic surfactant solutions in which concentrations vary from very low to above the theoretical CMCs. The color changes occur near the theoretical CMCs, presumably because the presence of surfactant micelles in the solution prevents the gold nanoparticles from aggregating. We have used gold nanoparticles as reporter probes to determine the concentrations of cationic surfactants in products such as hair conditioners, which often contain large amounts of alkyltrimethylammonium halides. Although this approach can only provide an estimate, it can be performed simply by addition of a given amount of gold nanoparticles to a series of diluted solutions, without the need for instruments or labor-intensive procedures.

  10. Preparation of stable suspensions of gold nanoparticles in water by sonoelectrochemistry.

    Science.gov (United States)

    Aqil, A; Serwas, H; Delplancke, J L; Jérôme, R; Jérôme, C; Canet, L

    2008-09-01

    Stable suspensions of gold nanoparticles in water were prepared with high yield by a novel one-step ultrasound assisted electrochemical process. Various strategies based on the addition of either tailor-made polymers or mixtures of commercially available polymers, in the electrochemical bath have been found successful to avoid nanoparticles aggregation commonly observed by sonoelectrochemistry. alpha-Methoxy-omega-mercapto-poly(ethylene oxide) or poly(vinyl pyrrolidone)/polyethylene oxide mixtures were able to build up a coalescence barrier around the gold nanoparticles. The results showed that the size of the gold nanoparticles could be easily tuned between 5 nm and 35 nm by simple control of the electrochemical parameters, i.e. the deposition time (T(ON)) from 10 ms to 20 ms. The properties of as-prepared gold nanoparticles were compared to the ones of gold colloids prepared by the more conventional wet nanoprecipitation method using chemical reductive agents.

  11. A Novel Route for the Preparation of Gold Nanoparticles in Polycaprolactone Nanofibers

    Directory of Open Access Journals (Sweden)

    Simón Yobanny Reyes-López

    2015-01-01

    Full Text Available A facile strategy for the fabrication of polycaprolactone (PCL nanofibers containing gold nanoparticles (AuNPs is proposed. The method is based on electrospinning nanosuspensions loaded with passivated Au nanoparticles. The optical property of gold nanoparticles synthesized was observed by UV-visible absorption spectra. Morphology and structure of the Au-PCL hybrid nanofibers were characterized by scanning electron microscopy, scanning transmission electron microscopy, and Fourier transformed infrared spectroscopy. The results of investigations by UV-visible and dynamic light scattering confirmed the presence of gold nanoparticles with diameters less than 10 nm. The STEM images show the presence of gold nanoparticles and gold agglomerates with diameter around 30 to 180 nm distributed over the surface of nanofibers, which is likely due to the increased incidence of agglomerations of AuNPs, due to drying process used.

  12. Lamellar multilayer hexadecylaniline-modified gold nanoparticle films deposited by the Langmuir-Blodgett technique

    Indian Academy of Sciences (India)

    Anita Swami; Ashavani Kumar; Murali Sastry

    2003-06-01

    Organization of hexadecylaniline (HDA)-modified colloidal gold particles at the air-water interface and the formation thereafter of lamellar, multilayer films of gold nanoparticles by the Langmuir-Blodgett technique is described in this paper. Formation of HDA-capped gold nanoparticles is accomplished by a simple biphasic mixture experiment wherein the molecule hexadecylaniline present in the organic phase leads to electrostatic complexation and reduction of aqueous chloroaurate ions, capping of the gold nanoparticles thus formed and phase transfer of the now hydrophobic particles into the organic phase. Organization of gold nanoparticles at the air-water interface is followed by surface pressure-area isotherm measurements while the formation of multilayer films of the nanoparticles by the Langmuir-Blodgett technique is monitored by quartz crystal microgravimetry, UVVis spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy.

  13. Biogenic silver and gold nanoparticles synthesized using red ginseng root extract, and their applications.

    Science.gov (United States)

    Singh, Priyanka; Kim, Yeon Ju; Wang, Chao; Mathiyalagan, Ramya; El-Agamy Farh, Mohamed; Yang, Deok Chun

    2016-05-01

    In the present study, we report a green methodology for the synthesis of silver and gold nanoparticles, using the root extract of the herbal medicinal plant Korean red ginseng. The silver and gold nanoparticles were synthesized within 1 h and 10 min respectively. The nanoparticles generated were not aggregated, and remained stable for a long time, which suggests the nature of nanoparticles. The phytochemicals and ginsenosides present in the root extract assist in reducing and stabilizing the synthesized nanoparticles. The red ginseng root extract-generated silver nanoparticles exhibit antimicrobial activity against pathogenic microorganisms including Vibrio parahaemolyticus, Staphylococcus aureus, Bacillus cereus, and Candida albicans. In addition, the silver nanoparticles exhibit biofilm degrading activity against S. aureus and Pseudomonas aeruginosa. Thus, the present study opens up a new possibility of synthesizing silver and gold nanoparticles in a green and rapid manner using Korean red ginseng root extract, and explores their biomedical applications.

  14. Characterization and catalytic activity of gold nanoparticles synthesized using ayurvedic arishtams.

    Science.gov (United States)

    Aromal, S Aswathy; Babu, K V Dinesh; Philip, Daizy

    2012-10-01

    The development of new synthesis methods for monodispersed nanocrystals using cheap and nontoxic chemicals, environmentally benign solvents and renewable materials remains a challenge to the scientific community. The present work reports a new green method for the synthesis of gold nanoparticles. Four different ayurvedic arishtams are used for the reduction of Au(3+) to Au nanoparticles. This method is simple, efficient, economic and nontoxic. Gold nanoparticles having different sizes in the range from 15 to 23 nm could be obtained. The nanoparticles have been characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles is evident from bright circular spots in the SAED pattern and peaks in the XRD pattern. The synthesized gold nanoparticles show good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH(4). The synthesized nanoparticles are found to exhibit size dependent catalytic property, the smaller nanoparticles showing faster activity.

  15. Laccase-Assisted Rapid Synthesis of Colloidal Gold Nanoparticles for the Catalytic Reduction of 4-Nitrophenol

    OpenAIRE

    Li, Fang; Li, Zheng; Zeng,Chang; Hu,Yonggang

    2017-01-01

    A green method for the rapid preparation of uniform-sized colloidal gold nanoparticles under ambient conditions was presented and validated using laccase as a reduction agent in alkaline medium. UV-Vis spectrophotometry, field-emission high-resolution transmission electron microscopy, X-ray diffraction, selected area electron diffraction, energy dispersive X-ray analysis, zetasizer, and Fourier transform infrared spectroscopy were used to characterize the gold nanoparticles. The gold nanopart...

  16. Study of Methylene Blue Degradation by Gold Nanoparticles Synthesized within Natural Zeolites

    OpenAIRE

    Ericka Rodríguez León; Eduardo Larios Rodríguez; César Rodríguez Beas; Germán Plascencia-Villa; Ramón Alfonso Iñiguez Palomares

    2016-01-01

    We carried out the in situ synthesis of gold nanoparticles inside a natural clinoptilolite-type zeolite matrix, using ascorbic acid as reducing agent. The microstructure of both zeolite and zeolite-gold nanocomposite was characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and Energy-Dispersive X-ray Spectroscopy (EDS) techniques. Size distribution as assessed by STEM indicated that 60% of gold nanoparticles measured l...

  17. The Green synthesis of gold nanoparticles using an aqueous root extract of Morinda citrifolia L.

    Science.gov (United States)

    Suman, T Y; Rajasree, S R Radhika; Ramkumar, R; Rajthilak, C; Perumal, P

    2014-01-24

    In the present work, we describe the synthesis of gold nanoparticles using an aqueous root extract of Morinda citrifolia. UV-vis spectroscopy, XRD, FTIR, FE-SEM, EDX and TEM were performed to characterize the formation of gold nanoparticles. The synthesized gold nanoparticles were characterized by a peak at 540 nm in the UV-vis spectrum. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (111), (200), (220) and (311) Bragg's reflections of cubic structure of metallic gold, respectively. The FTIR result showed that extract containing protein might be responsible for the formation of the nanoparticles and may play an important role in the stabilization of the formed nanoparticles. FESEM images revealed that the particles were triangle and mostly spherical in shape. TEM images clearly revealed the size of the nanoparticles were 12.17-38.26 nm in size.

  18. Surface Plasmons and Surface Enhanced Raman Spectra of Aggregated and Alloyed Gold-Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Y. Fleger

    2009-01-01

    Full Text Available Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR and surface enhanced Raman spectroscopy (SERS are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticles evaporated on top of larger gold nanoparticles show higher SERS than gold-silver alloyed nanoparticles, in spite of the fact that the SPR peak of alloyed nanoparticles is narrower and closer to the excitation wavelength. The highest Raman enhancement was obtained for substrates with a two-peak particle size distribution for excitation wavelengths close to the SPR.

  19. The Green synthesis of gold nanoparticles using an aqueous root extract of Morinda citrifolia L

    Science.gov (United States)

    Suman, T. Y.; Radhika Rajasree, S. R.; Ramkumar, R.; Rajthilak, C.; Perumal, P.

    2014-01-01

    In the present work, we describe the synthesis of gold nanoparticles using an aqueous root extract of Morinda citrifolia. UV-vis spectroscopy, XRD, FTIR, FE-SEM, EDX and TEM were performed to characterize the formation of gold nanoparticles. The synthesized gold nanoparticles were characterized by a peak at 540 nm in the UV-vis spectrum. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) Bragg's reflections of cubic structure of metallic gold, respectively. The FTIR result showed that extract containing protein might be responsible for the formation of the nanoparticles and may play an important role in the stabilization of the formed nanoparticles. FESEM images revealed that the particles were triangle and mostly spherical in shape. TEM images clearly revealed the size of the nanoparticles were 12.17-38.26 nm in size.

  20. Infrared attenuated total reflection spectroscopy for the characterization of gold nanoparticles in solution.

    Science.gov (United States)

    López-Lorente, Ángela Inmaculada; Sieger, Markus; Valcárcel, Miguel; Mizaikoff, Boris

    2014-01-07

    In situ synthesis of bare gold nanoparticles mediated by stainless steel as reducing agent was monitored via infrared attenuated total reflection (IR-ATR) spectroscopy. Gold nanoparticles were directly synthesized within the liquid cell of the ATR unit taking immediate advantage of the stainless steel walls of the ATR cell. As nanoparticles were formed, a layer of particles was deposited at the SiO2 ATR waveguide surface. Incidentally, the absorption bands of water increased resulting from surface-enhanced infrared absorption (SEIRA) effects arising from the presence of the gold nanoparticles within the evanescent field. Next to the influence of the Au(III) precursor concentration and the temperature, the suitability of IR-ATR spectroscopy as an innovative tool for investigating changes of nanoparticles in solution, including their aggregation promoted by an increase of the ionic strength or via a pH decrease, and for detailing the sedimentation process of gold nanoparticles was confirmed.

  1. Gold nanoparticles generated by thermolysis of "all-in-one" gold(I) carboxylate complexes.

    Science.gov (United States)

    Tuchscherer, A; Schaarschmidt, D; Schulze, S; Hietschold, M; Lang, H

    2012-03-07

    Consecutive synthesis methodologies for the preparation of the gold(I) carboxylates [(Ph(3)P)AuO(2)CCH(2)(OCH(2)CH(2))(n)OCH(3)] (n = 0-6) (6a-g) are reported, whereby selective mono-alkylation of diols HO(CH(2)CH(2)O)(n)H (n = 0-6), Williamson ether synthesis and metal carboxylate (Ag, Au) formation are the key steps. Single crystal X-ray diffraction studies of 6a (n = 0) and 6b (n = 1) were carried out showing that the P-Au-O unit is essentially linear. These compounds were applied in the formation of gold nanoparticles (NP) by a thermally induced decomposition process and hence the addition of any further stabilizing and reducing reagents, respectively, is not required. The ethylene glycol functionalities, providing multiple donating capabilities, are able to stabilise the encapsulated gold colloids. The dependency of concentration, generation time and ethylene glycol chain lengths on the NP size and size distribution is discussed. Characterisation of the gold colloids was performed by TEM, UV/Vis spectroscopy and electron diffraction studies revealing that Au NP are formed with a size of 3.3 (±0.6) to 6.5 (±0.9) nm in p-xylene with a sharp size distribution. Additionally, a decomposition mechanism determined by TG-MS coupling experiments of the gold(i) precursors is reported showing that 1(st) decarboxylation occurs followed by the cleavage of the Au-PPh(3) bond and finally release of ethylene glycol fragments to give Au-NP and the appropriate organics.

  2. Preparation, Physicochemical Characterization and Performance Evaluation of Gold Nanoparticles in Radiotherapy

    Directory of Open Access Journals (Sweden)

    Ali Kamiar

    2013-08-01

    Full Text Available Purpose: The aim of the present study was preparation, physicochemical characterization and performance evaluation of gold nanoparticles (GNPs in radiotherapy. Another objective was the investigation of anti-bacterial efficacy of gold nanoparticle against E. coli clinical strains. Methods: Gold nanoparticles prepared by controlled reduction of an aqueous HAuCl4 solution using Tri sodium citrate. Particle size analysis and Transmission electron microscopy were used for physicochemical characterization. Polymer gel dosimetry was used for evaluation of the enhancement of absorbed dose. Diffusion method in agar media was used for investigation of anti-bacterial effect. Results: Gold nanoparticles synthesized in size range from 57 nm to 346 nm by planning different formulation. Gold nanoparticle in 57 nm size increased radiation dose effectiveness with the magnitude of about 21 %. At the concentration of 400 ppm, Nano gold exhibited significant anti-bacterial effect against E. coli clinical strains. Conclusion: It is concluded that gold nanoparticles can be applied as dose enhancer in radiotherapy. The Investigation of anti-bacterial efficacy showed that gold nanoparticle had significant effect against E. coli clinical strains.

  3. Rapid colorimetric sensing of tetracycline antibiotics with in situ growth of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Li, E-mail: lishen97@163.com [Logistics School, Beijing Wuzi University, Beijing 101149 (China); Chen, Jing; Li, Na [Logistics School, Beijing Wuzi University, Beijing 101149 (China); He, Pingli [State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing 100094 (China); Li, Zhen [State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193 (China)

    2014-08-11

    Highlights: • Tetracyclines directly reduce aurate into gold nanoparticles. • Gold nanoparticles showed characteristic plamson absorbance at 526 nm. • Quantitative detection of tetracyclines with the colorimetric assay. • Tetracyclines spiked urine samples can be detected with the assay. - Abstract: A colorimetric assay utilizing the formation of gold nanoparticles was developed to detect tetracycline antibiotics in fluidic samples. Tetracycline antibiotics showed the capability of directly reducing aurate salts into atomic gold which form gold nanoparticles spontaneously under proper conditions. The resulted gold nanoparticles showed characteristic plasmon absorbance at 526 nm, which can be visualized by naked eyes or with a spectrophotometer. UV–vis absorbance of the resulted gold nanoparticles is correlated directly with the concentrations of tetracycline antibiotics in the solution, allowing for quantitative colorimetric detection of tetracycline antibiotics. Reaction conditions, such as pH, temperature, reaction time, and ionic strength were optimized. Sensitivity of the colorimetric assay can be enhanced by the addition of gold nanoparticle seeds, a LOD as low as 20 ng mL{sup −1} can be achieved with the help of seed particles. The colorimetric assay showed minimum interference from ethanol, methanol, urea, glucose, and other antibiotics such as sulfonamides, amino glycosides etc. Validity of the method was also evaluated on urine samples spiked with tetracycline antibiotics. The method provides a broad spectrum detection method for rapid and sensitive detection of reductive substances such as tetracycline antibiotics in liquid and biological samples.

  4. In situ gold nanoparticles formation: contrast agent for dental optical coherence tomography

    Science.gov (United States)

    Braz, Ana K. S.; Araujo, Renato E. de; Ohulchanskyy, Tymish Y.; Shukla, Shoba; Bergey, Earl J.; Gomes, Anderson S. L.; Prasad, Paras N.

    2012-06-01

    In this work we demonstrate the potential use of gold nanoparticles as contrast agents for the optical coherence tomography (OCT) imaging technique in dentistry. Here, a new in situ photothermal reduction procedure was developed, producing spherical gold nanoparticles inside dentinal layers and tubules. Gold ions were dispersed in the primer of commercially available dental bonding systems. After the application and permeation in dentin by the modified adhesive systems, the dental bonding materials were photopolymerized concurrently with the formation of gold nanoparticles. The gold nanoparticles were visualized by scanning electron microscopy (SEM). The SEM images show the presence of gold nanospheres in the hybrid layer and dentinal tubules. The diameter of the gold nanoparticles was determined to be in the range of 40 to 120 nm. Optical coherence tomography images were obtained in two- and three-dimensions. The distribution of nanoparticles was analyzed and the extended depth of nanosphere production was determined. The results show that the OCT technique, using in situ formed gold nanoparticles as contrast enhancers, can be used to visualize dentin structures in a non-invasive and non-destructive way.

  5. Tuning the structure of thermosensitive gold nanoparticle monolayers.

    Science.gov (United States)

    Rezende, Camila A; Shan, Jun; Lee, Lay-Theng; Zalczer, Gilbert; Tenhu, Heikki

    2009-07-23

    Gold nanoparticles grafted with poly(N-isopropylacrylamide) (PNIPAM) are rendered amphiphilic and thermosensitive. When spread on the surface of water, they form stable Langmuir monolayers that exhibit surface plasmon resonance. Using Langmuir balance and contrast-matched neutron reflectivity, the detailed structural properties of these nanocomposite monolayers are revealed. At low surface coverage, the gold nanoparticles are anchored to the interface by an adsorbed PNIPAM layer that forms a thin and compact pancake structure. Upon isothermal compression (T=20 degrees C), the adsorbed layer thickens with partial desorption of polymer chains to form brush structures. Two distinct polymer conformations thus coexist: an adsorbed conformation that assures stability of the monolayer, and brush structures that dangle in the subphase. An increase in temperature to 30 degrees C results in contractions of both adsorbed and brush layers with a concomitant decrease in interparticle distance, indicating vertical as well as lateral contractions of the graft polymer layer. The reversibility of this thermal response is also shown by the contraction-expansion of the polymer layers in heating-cooling cycles. The structure of the monolayer can thus be tuned by compression and reversibly by temperature. These compression and thermally induced conformational changes are discussed in relation to optical properties.

  6. Asymmetric gold nanoparticle reduction into polydimethylsiloxane thin films

    Science.gov (United States)

    Dunklin, Jeremy R.; Forcherio, Gregory T.; Berry, Keith R.; Roper, D. Keith

    2014-09-01

    Polymer thin films embedded with plasmonic gold nanoparticles (AuNPs) are of significant interest in biomedicine, optics, photovoltaic, and nanoelectromechanical systems. Thin polydimethylsiloxane (PDMS) films containing 3-7 micron layers of AuNPs that were fabricated with a novel diffusive-reduction synthesis technique attenuated up to 85% of incoming laser light at the plasmon resonance. Rapid diffusive reduction of AuNPs into asymmetric PDMS thin films provided superior optothermal capabilities relative to thicker films in which AuNPs were reduced throughout. A photonto- heat conversion of up to 3000°C/watt was demonstrated, which represents a 3-230-fold increase over previous AuNPfunctionalized systems. Optical attenuation and thermal response increased in proportion to order of magnitude increases in tetrachloroaurate (TCA) solution concentration. Optical and thermoplasmonic responses were observed with and without an adjacent mesh support, which increased attenuation but decreased thermal response. Morphological, optical, and thermoplasmonic properties of asymmetric AuNP-PDMS films varied significantly with diffusive TCA concentration. Gold nanoparticles, networks, and conglomerates were formed via reduction as the amount of dissolved TCA increased across a log10-scale. Increasing TCA concentrations caused polymer surface cratering, leading to a larger effective surface area. This method, utilizing the diffusion of TCA into a single exposed partially cured PDMS interface, could be used to replace expensive lithographic or solution synthesis of plasmon-functionalized systems.

  7. Piper betle-mediated green synthesis of biocompatible gold nanoparticles

    Science.gov (United States)

    Punuri, Jayasekhar Babu; Sharma, Pragya; Sibyala, Saranya; Tamuli, Ranjan; Bora, Utpal

    2012-08-01

    Here, we report the novel use of the ethonolic leaf extract of Piper betle for gold nanoparticle (AuNP) synthesis. The successful formation of AuNPs was confirmed by UV-visible spectroscopy, and different parameters such as leaf extract concentration (2%), gold salt concentration (0.5 mM), and time (18 s) were optimized. The synthesized AuNPs were characterized with different biophysical techniques such as transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). TEM experiments showed that nanoparticles were of various shapes and sizes ranging from 10 to 35 nm. FT-IR spectroscopy revealed that AuNPs were functionalized with biomolecules that have primary amine group -NH2, carbonyl group, -OH groups, and other stabilizing functional groups. EDX showed the presence of the elements on the surface of the AuNPs. FT-IR and EDX together confirmed the presence of biomolecules bounded on the AuNPs. Cytotoxicity of the AuNPs was tested on HeLa and MCF-7 cancer cell lines, and they were found to be nontoxic, indicating their biocompatibility. Thus, synthesized AuNPs have potential for use in various biomedical applications.

  8. Gold Nanoparticles-Enhanced Proton Exchange Membrane (PEM) Fuel Cell

    Science.gov (United States)

    Li, Hongfei; Pan, Cheng; Liu, Ping; Zhu, Yimei; Adzic, Radoslav; Rafailovich, Miriam

    Proton exchange membrane fuel cells have drawn great attention and been taken as a promising alternated energy source. One of the reasons hamper the wider application of PEM fuel cell is the catalytic poison effect from the impurity of the gas flow. Haruta has predicted that gold nanoparticles that are platelet shaped and have direct contact with the metal oxide substrate to be the perfect catalysts of the CO oxidization, yet the synthesis method is difficult to apply in the Fuel Cell. In our approach, thiol-functionalized gold nanoparticles were synthesized through two-phase method developed by Brust et al. We deposit these Au particles with stepped surface directly onto the Nafion membrane in the PEM fuel cell by Langmuir-Blodgett method, resulting in over 50% enhancement of the efficiency of the fuel cell. DFT calculations were conducted to understand the theory of this kind of enhancement. The results indicated that only when the particles were in direct surface contact with the membrane, where AuNPs attached at the end of the Nafion side chains, it could reduce the energy barrier for the CO oxidation that could happen at T<300K.

  9. Characterization of glucose oxidation by gold nanoparticles using nanoceria.

    Science.gov (United States)

    Lang, Nathan J; Liu, Biwu; Liu, Juewen

    2014-08-15

    Gold nanoparticles (AuNPs) can oxidize glucose, producing hydrogen peroxide and gluconic acid, which are the same products as those generated by glucose oxidase (GOx). In this regard, AuNPs are a nanozyme. Herein, a new colorimetric method is developed to understand the surface chemistry of gold nanoparticles for this oxidation reaction. The color of nanoceria is changed to yellow by the hydrogen peroxide generated during glucose oxidation. Using this assay, we find that adsorption of small molecules such as citrate does not deactivate AuNPs, while adsorption of polymers including serum proteins and high molecular weight polyethylene glycol inhibits glucose oxidation. In addition to glucose, AuNPs can also oxidize galactose. Therefore, this reaction is unlikely to be directly useful for glucose detection for biomedical applications. On the other hand, AuNPs might serve as a general oxidase for a broad range of substrates. The glucose oxidation reaction is slower at lower pH. Since the reaction generates an acid product, glucose oxidation becomes slower as the reaction proceeds. The effects of temperature, AuNP size, and reaction kinetics have been systematically studied. This work provides new insights regarding the surface chemistry of AuNPs as a nanozyme.

  10. Gold-functionalized magnetic nanoparticles restrict growth of Pseudomonas aeruginosa

    Science.gov (United States)

    Niemirowicz, Katarzyna; Swiecicka, Izabela; Wilczewska, Agnieszka Z; Misztalewska, Iwona; Kalska-Szostko, Beata; Bienias, Kamil; Bucki, Robert; Car, Halina

    2014-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) and their derivatives (aminosilane and gold-coated) have been widely investigated in numerous medical applications, including their potential to act as antibacterial drug carriers that may penetrate into bacteria cells and biofilm mass. Pseudomonas aeruginosa is a frequent cause of infection in hospitalized patients, and significant numbers of currently isolated clinical strains are resistant to standard antibiotic therapy. Here we describe the impact of three types of SPIONs on the growth of P. aeruginosa during long-term bacterial culture. Their size, structure, and physicochemical properties were determined using transmission electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy. We observed significant inhibition of P. aeruginosa growth in bacterial cultures continued over 96 hours in the presence of gold-functionalized nanoparticles (Fe3O4@Au). At the 48-hour time point, growth of P. aeruginosa, as assessed by the number of colonies grown from treated samples, showed the highest inhibition (decreased by 40%). These data provide strong evidence that Fe3O4@Au can dramatically reduce growth of P. aeruginosa and provide a platform for further study of the antibacterial activity of this nanomaterial. PMID:24855358

  11. A new green chemistry method based on plant extracts to synthesize gold nanoparticles

    Science.gov (United States)

    Montes Castillo, Milka Odemariz

    Extraordinary chemical and physical properties exhibited by nanomaterials, as compared to their bulk counterparts, have made the area of nanotechnology a growing realm in the past three decades. It is the nanoscale size (from 1 to 100 nm) and the morphologies of nanomaterials that provide several properties and applications not possible for the same material in the bulk. Magnetic and optical properties, as well as surface reactivity are highly dependent on the size and morphology of the nanomaterial. Diverse nanomaterials are being widely used in molecular diagnostics as well as in medicine, electronic and optical devices. Among the most studied nanomaterials, gold nanoparticles are of special interest due to their multifunctional capabilities. For instance, spherical gold nanoparticles measuring 15-20 nm in diameter have been studied due to their insulin binding properties. Also, thiol functionalized gold nanoparticles between 5 and 30 nm are used in the detection of DNA. Thus, harnessing the shape and size of gold nanoparticles plays an important role in science and technology. The synthesis of gold nanoparticles via the reduction of gold salts, using citrate or other reducing agents, has been widely studied. In recent years, algae, fungi, bacteria, and living plants have been used to reduce trivalent gold (Au3+) to its zero oxidation state (Au 0) forming gold nanoparticles of different sizes and shapes. In addition, plant biomasses have also been studied for their gold-reducing power and nanoparticle formation. Although there is information about the synthesis of the gold nanoparticles by biologically based materials; to our knowledge, the study of the use of alfalfa extracts has not been reported. This innovation represents a significant improvement; that is an environmentally friendly method that does not use toxic chemicals. Also, the problem of extracting the formed gold nanoparticles from biomaterials is addressed in this research but still remains to be

  12. Silver, Gold, Palladium Nanoparticles: Ligand Design, Synthesis and Polymer Composites

    Science.gov (United States)

    Iqbal, Muhammad

    Metal nanoparticles, especially gold nanoparticles (AuNPs), have been extensively studied due to their interesting optical properties and potential applications in emerging technologies like drug delivery, cancer therapy, catalysis, chemical and bio-sensing and microelectronics devices. Alkyl thiol ligands in the form of self assembled monolayers are often used to stabilize and functionalize the gold nanoparticles while other types of ligands have been rarely employed and the properties of AuNPs protected by different types of ligands have not been studied comprehensively and comparatively. This dissertation reports the first comparative studies on the thermal and chemical stability of AuNPs protected by alkyl thiolates, alkyl selenolates, dialkyl dithiophosphinates, and dialkyl dithiophosphates (Chapters 2 and 3). AuNPs protected by dialkyl dithiophosphinates and dialkyl dithiophosphates are unprecedented. All AuNPs were prepared from amine protected precursor AuNPs by ligand exchange to ensure similar size, size distribution, and chemical composition. They were extensively characterized by solution 1H-NMR and UV-VIS spectroscopy, transmission electron microscopy (TEM), thermal analysis, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis. For the first time, thermal stability was investigated by differential scanning calorimetry (DSC) that provided more accurate decomposition temperatures and enthalpies, whereas chemical stability was tested as the availability of the gold surface towards etching with cyanide in different solvents. Surprisingly, alkyl selenolate protected AuNPs are thermally less stable than alkyl thiolate protected AuNPs despite their proposed stronger binding to the gold surface and a much more crystalline monolayer, which suggests that different decomposition mechanisms apply to alkyl thiolate and alkyl selenolate protected AuNPs. Dialkyl dithiophosphinates and dialkyl dithiophosphates protected AuNPs are thermally

  13. Green synthesis of gold nanoparticles using Stevia rebaudiana leaf extracts: Characterization and their stability.

    Science.gov (United States)

    Sadeghi, Babak; Mohammadzadeh, M; Babakhani, B

    2015-07-01

    Various methods invented and developed for the synthesis of gold nanoparticles that increases daily consumed. According to this method, including potential environmental pollution problems and the complexity of the synthesis, in this study, the feasibility of using the leaves extract of Stevia rebaudiana (SR) for the reduction of gold ions to nanoparticles form have been studied. Stevia leaves were used to prepare the aqueous extract for this study. Gold nanoparticles were characterized with different techniques such as UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Transmission electron microscopy experiments showed that these nanoparticles are spherical and uniformly distributed and its size is from 5 to 20 nm. FT-IR spectroscopy revealed that gold nanoparticles were functionalized with biomolecules that have primary amine group (NH2), carbonyl group, OH groups and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face centered cubic structure of gold nanoparticles with size of 17 nm. The scanning electron microscopy (SEM) implies the right of forming gold nanoparticles. The results, confirm that gold nanoparticles have synthesized by the leaves extract of S. rebaudiana (SR).

  14. Root extracts of Polygala tenuifolia for the green synthesis of gold nanoparticles.

    Science.gov (United States)

    Jun, Sang Hui; Kim, Hyun-Seok; Koo, Yean Kyoung; Park, Yohan; Kim, Jinwoong; Cho, Seonho; Park, Youmie

    2014-08-01

    Traditional medicinal plants possess diverse active constituents for exerting their biological activities. Recently, the innovative applications of plant extracts have revealed their promise as 'green' reducing agents for the reduction of metal ions during the synthesis of metallic nanoparticles. Herein, we report the use of 70% ethanol extracts from Polygala tenuifolia roots as a 'green' reducing agent for the production of gold nanoparticles by reducing gold(III) chloride trihydrate. Gold nanoparticles were characterized using UV-Visible spectrophotometry, high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The gold nanoparticles had characteristic surface plasmon resonance bands at 535 nm. HR-TEM and AFM images revealed major spherical-shaped nanoparticles. The average diameter was measured to be 9.77±3.09 nm using HR-TEM images. The crystalline structure of the gold nanoparticles was confirmed through lattice fringes and circular spots within the selected area electron diffraction in the HR-TEM images along with the XRD peaks. The gold nanoparticles exhibited enhanced anticoagulant activity, as assessed by activated partial thromboplastin time. The current method is a straightforward, environmentally friendly, and inexpensive method for the production of gold nanoparticles using extracts from traditional medicinal plants.

  15. Green Chemistry Approach for the Synthesis of Gold Nanoparticles Using the Fungus Alternaria sp.

    Science.gov (United States)

    Dhanasekar, Naresh Niranjan; Rahul, Ganga Ravindran; Narayanan, Kannan Badri; Raman, Gurusamy; Sakthivel, Natarajan

    2015-07-01

    The synthesis of gold nanoparticles has gained tremendous attention owing to their immense applications in the field of biomedical sciences. Although several chemical procedures are used for the synthesis of nanoparticles, the release of toxic and hazardous by-products restricts their use in biomedical applications. In the present investigation, gold nanoparticles were synthesized biologically using the culture filtrate of the filamentous fungus Alternaria sp. The culture filtrate of the fungus was exposed to three different concentrations of chloroaurate ions. In all cases, the gold ions were reduced to Au(0), leading to the formation of stable gold nanoparticles of variable sizes and shapes. UV-Vis spectroscopy analysis confirmed the formation of nanoparticles by reduction of Au(3+) to Au(0). TEM analysis revealed the presence of spherical, rod, square, pentagonal, and hexagonal morphologies for 1 mM chloroaurate solution. However, quasi-spherical and spherical nanoparticles/heart-like morphologies with size range of about 7-13 and 15-18 nm were observed for lower molar concentrations of 0.3 and 0.5 mM gold chloride solution, respectively. The XRD spectrum revealed the face-centered cubic crystals of synthesized gold nanoparticles. FT-IR spectroscopy analysis confirmed the presence of aromatic primary amines, and the additional SPR bands at 290 and 230 nm further suggested that the presence of amino acids such as tryptophan/tyrosine or phenylalanine acts as the capping agent on the synthesized mycogenic gold nanoparticles.

  16. Green synthesis and nanotopography of heparin-reduced gold nanoparticles with enhanced anticoagulant activity.

    Science.gov (United States)

    Kim, Hyun-Seok; Jun, Sang Hui; Koo, Yean Kyoung; Cho, Seonho; Park, Youmie

    2013-03-01

    This paper reports on the green synthesis of heparin-reduced gold nanoparticles and their nanotopography as studied with atomic force microscopy. The study also evaluated the anticoagulant activity of the newly prepared gold nanoparticles. The heparin-reduced gold nanoparticles were homogeneous, showing characteristic surface plasmon resonance bands of approximately 523-527 nm, and their shapes were mostly spherical and amorphous. The average diameter of the nanoparticles measured from atomic force microscopic images was either 20.26 +/- 3.35 nm or 40.85 +/- 8.95 nm depending on the different precursor salts and heparin concentrations. Atomic force microscopic images revealed that the topography of the heparin polymer aggregated when deposited onto mica, resembling a chain of mountains. This characteristic nanotopography of the heparin disappeared after the synthesis of the gold nanoparticles was performed. Interestingly, prolonged prothrombin time, thrombin time, and activated partial thromboplastin time were observed in the heparin-reduced gold nanoparticles when compared to a control heparin, suggesting the enhancement of anticoagulant activity in heparin-reduced gold nanoparticles. Hence, the green synthesis of gold nanoparticles with heparin using a simple reaction step could be a viable procedure for enhancing heparin's anticoagulant activity.

  17. Substrate decomposition in galvanic displacement reaction: Contrast between gold and silver nanoparticle formation

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Tapas; Satpati, Biswarup, E-mail: biswarup.satpati@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700 064 (India); Kabiraj, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067 (India)

    2015-06-24

    We have investigated substrate decomposition during formation of silver and gold nanoparticles in galvanic displacement reaction on germanium surfaces. Silver and gold nanoparticles were synthesized by electroless deposition on sputter coated germanium thin film (∼ 200 nm) grown initially on silicon substrate. The nanoparticles formation and the substrate corrosion were studied using scanning transmission electron microscopy (STEM) and the energy dispersive X-ray (EDX) spectroscopy.

  18. Heterogeneous multiscale Monte Carlo simulations for gold nanoparticle radiosensitization.

    Science.gov (United States)

    Martinov, Martin P; Thomson, Rowan M

    2017-02-01

    To introduce the heterogeneous multiscale (HetMS) model for Monte Carlo simulations of gold nanoparticle dose-enhanced radiation therapy (GNPT), a model characterized by its varying levels of detail on different length scales within a single phantom; to apply the HetMS model in two different scenarios relevant for GNPT and to compare computed results with others published. The HetMS model is implemented using an extended version of the EGSnrc user-code egs_chamber; the extended code is tested and verified via comparisons with recently published data from independent GNP simulations. Two distinct scenarios for the HetMS model are then considered: (a) monoenergetic photon beams (20 keV to 1 MeV) incident on a cylinder (1 cm radius, 3 cm length); (b) isotropic point source (brachytherapy source spectra) at the center of a 2.5 cm radius sphere with gold nanoparticles (GNPs) diffusing outwards from the center. Dose enhancement factors (DEFs) are compared for different source energies, depths in phantom, gold concentrations, GNP sizes, and modeling assumptions, as well as with independently published values. Simulation efficiencies are investigated. The HetMS MC simulations account for the competing effects of photon fluence perturbation (due to gold in the scatter media) coupled with enhanced local energy deposition (due to modeling discrete GNPs within subvolumes). DEFs are most sensitive to these effects for the lower source energies, varying with distance from the source; DEFs below unity (i.e., dose decreases, not enhancements) can occur at energies relevant for brachytherapy. For example, in the cylinder scenario, the 20 keV photon source has a DEF of 3.1 near the phantom's surface, decreasing to less than unity by 0.7 cm depth (for 20 mg/g). Compared to discrete modeling of GNPs throughout the gold-containing (treatment) volume, efficiencies are enhanced by up to a factor of 122 with the HetMS approach. For the spherical phantom, DEFs vary with time for diffusion

  19. Production of gold nanoparticles by Streptomyces djakartensis isolate B-5

    Directory of Open Access Journals (Sweden)

    Sara Biglari

    2014-09-01

    Full Text Available  Objective(s: Biosynthesis of gold nanoparticles (NGPs is environmentally safer than chemical and physical procedures. This method requires no use of toxic solvents and synthesis of dangerous products and is environmentally safe. In this study, we report the biosynthesis of NGPs using Streptomyces djakartensis isolate B-5. Materials and Methods: NGPs were biosynthesized by reducing aqueous gold chloride solution via a Streptomyces isolate without the need for any additive for protecting nanoparticles from aggregation. We characterized the responsible Streptomycete; its genome DNA was isolated, purified and 16S rRNA was amplified by PCR. The amplified isolate was sequenced; using the BLAST search tool from NCBI, the microorganism was identified to species level. Results: Treating chloroauric acid solutions with this bacterium resulted in reduction of gold ions and formation of stable NGPs. TEM and SEM electro micrographs of NGPs indicated size range from 2- 25 nm with average of 9.09 nm produced intracellular by the bacterium. SEM electro micrographs revealed morphology of spores and mycelia. The amplified PCR fragment of 16S rRNA gene was cloned and sequenced from both sides; it consisted of 741 nucleotides. According to NCBI GenBank, the bacterium had 97.1% homology with Streptomyces djakartensis strain RT-49. The GenBank accession number for partial 16S rRNA gene was recorded as JX162550. Conclusion: Optimized application of such findings may create applications of Streptomycetes for use as bio-factories in eco-friendly production of NGPs to serve in demanding industries and related biomedical areas. Research in this area should also focus on the unlocking the full mechanism of NGPs biosynthesis by Streptomycetes.

  20. Multiple Resonances Induced by Plasmonic Coupling between Gold Nanoparticle Trimers and Hexagonal Assembly of Gold-Coated Polystyrene Microspheres.

    Science.gov (United States)

    Uchida, Takako; Yoshikawa, Takayasu; Tamura, Mamoru; Iida, Takuya; Imura, Kohei

    2016-09-15

    Optical properties of a gold nanoparticle trimer assembly coupled with gold-coated hexagonally close-packed polystyrene microspheres were investigated by linear and nonlinear spectroscopy. The observed reflection spectrum shows multiple peaks from the visible to near-infrared spectral regions. The spectroscopic properties were also examined by a finite-difference time-domain simulation. We found that the optical response of plasmons excited in the gold nanoparticle trimers was significantly modulated by strong coupling of the plasmons and the photonic mode induced in the gold-coated polystyrene assembly. Two-photon induced photoluminescence and Raman scattering from the sample were investigated, and both signals were significantly enhanced at the gold nanoparticle assembly. The simulations reveal that the electric fields can be enhanced site-selectively, not only at the interstitial sites in the nanoparticle assembly but also at the gaps between the particle and the gold film due to plasmonic interactions, by tuning the wavelength and are responsible for the strong optical responses.

  1. Biodistribution of colloidal gold nanoparticles after intravenous administration: effect of particle size.

    Science.gov (United States)

    Sonavane, Ganeshchandra; Tomoda, Keishiro; Makino, Kimiko

    2008-10-15

    Purpose of the present research work was to evaluate the biological distribution of differently size gold nanoparticles (NP) up on intravenous administration in mice. Another objective was to study effect of particle size on biological distribution of gold NP to enable their diverse applications in nanotechnology. Gold NP of different particle sizes, mainly 15, 50, 100 and 200 nm, were synthesized by modifying citrate ion concentration. Synthesized gold nanoparticles were characterized by SEM and their size distribution was studied by particle size analyzer. Gold NP was suspended in sodium alginate solution (0.5%, w/v) and administered to mice (1g/kg, intravenously) [n=3]. After 24h of administration of gold NP, blood was collected under light ether anesthesia, mice were sacrificed by cervical dislocation and various tissues/organs were removed. The tissues were then washed with saline, homogenized and lysed with aqua regia. The determination of gold in samples was carried out quantitatively by inductively coupled plasma mass spectrometry (ICP-MS). SEM study revealed spherical morphology of gold NP with narrow particle size distribution. Biodistribution study revealed gold NPs of all sizes were mainly accumulated in organs like liver, lung and spleen. The accumulation of gold NP in various tissues was found to be depending on particle size. 15 nm gold NP revealed higher amount of gold and number of particles in all the tissues including blood, liver, lung, spleen, kidney, brain, heart, stomach. Interestingly, 15 and 50 nm gold NP were able to pass blood-brain barrier as evident from gold concentration in brain. Two-hundred nanometers gold NP showed very minute presence in organs including blood, brain, stomach and pancreas. The results revealed that tissue distribution of gold nanoparticles is size-dependent with the smallest 15 nm nanoparticles showing the most widespread organ distribution.

  2. Ultrasmall gold nanoparticles anchored to graphene and enhanced photothermal effects by laser irradiation of gold nanostructures in graphene oxide solutions.

    Science.gov (United States)

    Zedan, Abdallah F; Moussa, Sherif; Terner, James; Atkinson, Garrett; El-Shall, M Samy

    2013-01-22

    In this work we demonstrate the coupling of the photothermal effects of gold nanostructures of controlled size and shape with graphene oxide nanosheets dispersed in water. The enhanced photothermal effects can be tuned by controlling the shape and size of the gold nanostructures, which result in a remarkable increase in the heating efficiency of the laser-induced size reduction of gold nanostructures. The Raman spectra of the Au-graphene nanosheets provide direct evidence for the presence of more structural defects in the graphene lattice induced by laser irradiation of graphene oxide nanosheets in the presence of Au nanostructures. The large surface areas of the laser-reduced graphene oxide nanosheets with multiple defect sites and vacancies provide efficient nucleation sites for the ultrasmall gold nanoparticles with diameters of 2-4 nm to be anchored to the graphene surface. This defect filling mechanism decreases the mobility of the ultrasmall gold nanoparticles and, thus, stabilizes the particles against the Ostwald ripening process, which leads to a broad size distribution of the laser-size-reduced gold nanoparticles. The Au nanostructures/graphene oxide solutions and the ultrasmall gold-graphene nanocomposites are proposed as promising materials for photothermal therapy and for the efficient conversion of solar energy into usable heat for a variety of thermal, thermochemical, and thermomechanical applications.

  3. Toxicity of silver and gold nanoparticles on marine microalgae.

    Science.gov (United States)

    Moreno-Garrido, Ignacio; Pérez, Sara; Blasco, Julián

    2015-10-01

    The increased use of nanomaterials in several novel industrial applications during the last decade has led to a rise in concerns about the potential toxic effects of released engineered nanoparticles (NPs) into the environment, as their potential toxicity to aquatic organisms is just beginning to be recognised. Toxicity of metallic nanoparticles to aquatic organisms, including microalgae, seems to be related to their physical and chemical properties, as well as their behaviour in the aquatic media where processes of dissolution, aggregation and agglomeration can occur. Although the production of these particles has increased considerably in recent years, data on their toxicity on microalgae, especially those belonging to marine or estuarine environments remain scarce and scattered. The literature shows a wide variation of results on toxicity, mainly due to the different methodology used in bioassays involving microalgae. These can range for up to EC50 data, in the case of AgNPs, representing five orders of magnitude. The importance of initial cellular density is also addressed in the text, as well as the need for keeping test conditions as close as possible to environmental conditions, in order to increase their environmental relevance. This review focuses on the fate and toxicity of silver, gold, and gold-silver alloy nanoparticles on microalgae, as key organisms in aquatic ecosystems. It is prompted by their increased production and use, and taking into account that oceans and estuaries are the final sink for those NPs. The design of bioassays and further research in the field of microalgae nanoecotoxicology is discussed, with a brief survey on newly developed technology of green (algae mediated) production of Ag, Au and Ag-Au bimetallic NPs, as well as some final considerations about future research on this field. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Coating of gold nanoparticles for medical application: UV-VIS

    Science.gov (United States)

    Martínez Espinosa, Juan Carlos; Ramírez, Nayem Amtanus Chequer; Funes Oliva, Luis Enrique; Córdova Fraga, Teodoro; Bernal Alvarado, Jesús; Reyes Pablo, Aldelmo; Núñez, Anita Rosa Elvira

    2014-11-01

    The use of nanostructured materials has gained strength in recent years in the biomedical area; new applications such as the detection of components in living cells have been used in pharmaceutical area, specifically to study the interaction of various antitumor drugs in living tissues, the detection of genes that are closely related to some type of cancer, as well as the detections of protein biomarkers for diseases also have been studied in various research laboratories around of the world. In this work, we characterize the variation of the absorbance of gold nanoparticles (GNPs) coated with different concentration of Bovine Serum Albumin (BSA) protein. We use GNPS of 60 nm of the trademark-TED PELLA, the BSA protein trademark of Sigma Aldrich and based on that proposed protocol by Chithrani et al., 2009 with purposes to obtain an alternative model to determine the optimal stability of the nanoparticles coated with the protein. The colloidal solutions were prepared with BSA at different concentrations (0.25, 0.5, 0.75 and 1% M/V), and were centrifuged at 15,000 rpm for 90 minutes (centrifuge Model Z383K) and a constant temperature of 25 °C. All the spectra sets were obtained within the range from 400 to 700 nm using an UV-VIS spectrophotometer (Thermo Scientific Model 51118650). The results showed a R2 of 0.99 for an exponential curve correlation between the concentration of BSA, and the absorbance measured. We found at higher concentrations of BSA, there is a decrease in the intensity of the absorption spectra in the plasmon resonance. This preliminary model obtained can be used in the stabilization of gold nanoparticles with different proteins of biomedical interest in future experiments and support for functionalization of GNPs with specific membrane markers.

  5. Colorimetric As (V) detection based on S-layer functionalized gold nanoparticles.

    Science.gov (United States)

    Lakatos, Mathias; Matys, Sabine; Raff, Johannes; Pompe, Wolfgang

    2015-11-01

    Herein, we present simple and rapid colorimetric and UV/VIS spectroscopic methods for detecting anionic arsenic (V) complexes in aqueous media. The methods exploit the aggregation of S-layer-functionalized spherical gold nanoparticles of sizes between 20 and 50 nm in the presence of arsenic species. The gold nanoparticles were functionalized with oligomers of the S-layer protein of Lysinibacillus sphaericus JG-A12. The aggregation of the nanoparticles results in a color change from burgundy-red for widely dispersed nanoparticles to blue for aggregated nanoparticles. A detailed signal analysis was achieved by measuring the shift of the particle plasmon resonance signal with UV/VIS spectroscopy. To further improve signal sensitivity, the influence of larger nanoparticles was tested. In the case of 50 nm gold nanoparticles, a concentration of the anionic arsenic (V) complex lower than 24 ppb was detectable.

  6. Modifying the chemistry of graphene with substrate selection: A study of gold nanoparticle formation

    Energy Technology Data Exchange (ETDEWEB)

    Zaniewski, Anna M.; Trimble, Christie J.; Nemanich, Robert J. [Department of Physics, Arizona State University, Tempe, Arizona 85281 (United States)

    2015-03-23

    Graphene and metal nanoparticle composites are a promising class of materials with unique electronic, optical, and chemical properties. In this work, graphene is used as a reducing surface to grow gold nanoparticles out of solution-based metal precursors. The nanoparticle formation is found to strongly depend upon the graphene substrate selection. The studied substrates include diamond, p-type silicon, aluminum oxide, lithium niobate, and copper. Our results indicate that the chemical properties of graphene depend upon this selection. For example, for the same reaction times and concentration, the reduction of gold chloride to gold nanoparticles on graphene/lithium niobate results in 3% nanoparticle coverage compared to 20% coverage on graphene/silicon and 60% on graphene/copper. On insulators, nanoparticles preferentially form on folds and edges. Energy dispersive X-ray analysis is used to confirm the nanoparticle elemental makeup.

  7. Layer-by-Layer Assembly Onto Gold Nanoparticles of Various Size

    Science.gov (United States)

    Kilroy, Andrew; Kessler, Sarah; Dobbins, Tabbetha

    This research focuses on the potential applications of coated gold nanoparticles in medicine. By coating gold nanoparticles in layers of polyelectrolytes, with a final layer of antibodies which targets chemicals uniquely exhibited by cancer cells, we eventually hope to selectively attach the nanoparticles to the cancer cells. The coated nanoparticles are assembled through layer-by-layer coulombic attraction due to the passive zeta potential of the particle and the charged nature of the polyelectrolytes. This poster will explore the potential usefulness of variously sized nanoparticles with various thickness of polyelectrolyte layers.

  8. Gold nanoparticles delivery in mammalian live cells: a critical review

    Directory of Open Access Journals (Sweden)

    Raphaël Lévy

    2010-02-01

    Full Text Available Functional nanomaterials have recently attracted strong interest from the biology community, not only as potential drug delivery vehicles or diagnostic tools, but also as optical nanomaterials. This is illustrated by the explosion of publications in the field with more than 2,000 publications in the last 2 years (4,000 papers since 2000; from ISI Web of Knowledge, ‘nanoparticle and cell’ hit. Such a publication boom in this novel interdisciplinary field has resulted in papers of unequal standard, partly because it is challenging to assemble the required expertise in chemistry, physics, and biology in a single team. As an extreme example, several papers published in physical chemistry journals claim intracellular delivery of nanoparticles, but show pictures of cells that are, to the expert biologist, evidently dead (and therefore permeable. To attain proper cellular applications using nanomaterials, it is critical not only to achieve efficient delivery in healthy cells, but also to control the intracellular availability and the fate of the nanomaterial. This is still an open challenge that will only be met by innovative delivery methods combined with rigorous and quantitative characterization of the uptake and the fate of the nanoparticles. This review mainly focuses on gold nanoparticles and discusses the various approaches to nanoparticle delivery, including surface chemical modifications and several methods used to facilitate cellular uptake and endosomal escape. We will also review the main detection methods and how their optimum use can inform about intracellular localization, efficiency of delivery, and integrity of the surface capping. Raphaël Lévy is a BBSRC David Phillips Research Fellow at the University of Liverpool. He graduated in Physics at the University Louis Pasteur in Strasbourg (France. In 2002, after a Master in Soft Condensed Matter Physics, he obtained a PhD in Physics at the University Louis Pasteur. He then moved to

  9. Analytical detection and biological assay of antileukemic drug using gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Selvaraj, V. [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India)]. E-mail: rajselva_77@yahoo.co.in; Alagar, M. [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India)]. E-mail: mkalagar@yahoo.com; Hamerton, I. [Chemistry Division, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

    2006-11-12

    Gold nanoparticles are reported and evaluated as probes for the detection of anticancer drug 6-mercaptopurine (6-MP). The nature of binding between 6-MP and the gold nanoparticles via complexation is investigated using ultraviolet-visible spectrum, cyclic voltammetry, transmission electron microscopy, fluorescence and Fourier transform infrared (FT-IR) spectroscopy. The bound antileukemic drug is fluorescent and the quenching property of gold nanoparticles could be exploited for biological investigations. The 6-MP-colloidal gold complex is observed to have appreciable antibacterial and antifungal activity against Micrococcus luteus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Aspergillus fumigatus, and Aspergillus niger. The experimental studies suggest that gold nanoparticles have the potential to be used as effective carriers for anticancer drugs.

  10. Glucoxylan-mediated green synthesis of gold and silver nanoparticles and their phyto-toxicity study.

    Science.gov (United States)

    Iram, Fozia; Iqbal, Mohammad S; Athar, Muhammad M; Saeed, Muhammad Z; Yasmeen, Abida; Ahmad, Riaz

    2014-04-15

    A green synthesis of gold and silver nanoparticles having exceptional high stability is reported. The synthesis involves the use of glucoxylans isolated from seeds of Mimosa pudica and excludes the use of conventional reducing and capping agents. The average particle sizes were 40 and 6 nm for gold and silver, respectively. The size of gold particles obtained in this work is suitable for drug delivery as they are non-cytotoxic. In phyto-toxicity tests the gold and silver nanoparticles did not show any significant effect on germination of radish seeds, whereas in radish seedling root growth assay the two particles behaved differently. The silver nanoparticles exhibited a concentration-dependent stimulatory effect on root length, whereas the gold nanoparticles had no significant effect in this test. The likely mechanism of these effects is discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Synthesis and characterization of silver and gold nanoparticles in ionic liquid

    Science.gov (United States)

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

    2009-07-01

    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.

  12. Photoluminescence decay rate of silicon nanoparticles modified with gold nanoislands

    Science.gov (United States)

    Dan'ko, Viktor; Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro

    2014-04-01

    We investigated plasmon-assisted enhancement of emission from silicon nanoparticles (ncs-Si) embedded into porous SiO x matrix in the 500- to 820-nm wavelength range. In the presence in the near-surface region of gold nanoisland film, ncs-Si exhibited up to twofold luminescence enhancement at emission frequencies that correspond to the plasmon resonance frequency of Au nanoparticles. Enhancement of the photoluminescence (PL) intensity was attributed to coupling with the localized surface plasmons (LSPs) excited in Au nanoparticles and to increase in the radiative decay rate of ncs-Si . It has been shown that spontaneous emission decay rate of ncs-Si modified by thin Au film over the wide emission spectral range was accelerated. The emission decay rate distribution was determined by fitting the experimental decay curves to the stretched exponential model. The observed increase of the PL decay rate distribution width for the Au-coated nc-Si-SiO x sample in comparison with the uncoated one was explained by fluctuations in the surface-plasmon excitation rate .

  13. Assembly of citrate gold nanoparticles on hydrophilic monolayers

    Science.gov (United States)

    Vikholm-Lundin, Inger; Rosqvist, Emil; Ihalainen, Petri; Munter, Tony; Honkimaa, Anni; Marjomäki, Varpu; Albers, Willem M.; Peltonen, Jouko

    2016-08-01

    Self-assembled monolayers (SAMs) as model surfaces were linked onto planar gold films thorough lipoic acid or disulfide groups. The molecules used were polyethylene glycol (EG-S-S), N-[tris-(hydroxymethyl)methyl]acrylamide polymers with and without lipoic acid (Lipa-pTHMMAA and pTHMMAA) and a lipoic acid triazine derivative (Lipa-MF). All the layers, but Lipa-MF with a primary amino group were hydroxyl terminated. The layers were characterized by contact angle measurements and atomic force microscopy, AFM. Citrate stabilized nanoparticles, AuNPs in water and phosphate buffer were allowed to assemble on the layers for 10 min and the binding was followed in real-time with surface plasmon resonance, SPR. The SPR resonance curves were observed to shift to higher angles and become increasingly damped, while also the peaks strongly broaden when large nanoparticles assembled on the surface. Both the angular shift and the damping of the curve was largest for nanoparticles assembling on the EG-S-S monolayer. High amounts of particles were also assembled on the pTHMMAA layer without the lipoic acid group, but the damping of the curve was considerably lower with a more even distribution of the particles. Topographical images confirmed that the highest number of particles were assembled on the polyethylene glycol monolayer. By increasing the interaction time more particles could be assembled on the surface.

  14. Spectroscopic properties of multilayered gold nanoparticle 2D sheets.

    Science.gov (United States)

    Yoshida, Akihito; Imazu, Keisuke; Li, Xinheng; Okamoto, Koichi; Tamada, Kaoru

    2012-12-11

    We report the fabrication technique and optical properties of multilayered two-dimensional (2D) gold nanoparticle sheets ("Au nanosheet"). The 2D crystalline monolayer sheet composed of Au nanoparticles shows an absorption peak originating from a localized surface plasmon resonance (LSPR). It was found that the absorption spectra dramatically change when the monolayers are assembled into the multilayers on different substrates (quartz or Au). In the case of the multilayers on Au thin film (d = 200 nm), the LSPR peak is shifted to longer wavelength at the near-IR region by increasing the number of layers. The absorbance also depends on the layer number and shows the nonlinear behavior. On the other hand, the multilayers on quartz substrate show neither such LSPR peak shift nor nonlinear response of absorbance. The layer number dependence on metal surfaces can be interpreted as the combined effects between the near-field coupling of the LSPR and the far-field optics of the stratified metamaterial films, as proposed in our previous study. We also report the spectroscopic properties of hybrid multilayers composed of two kinds of monolayers, i.e., Au nanosheet and Ag nanosheet. The combination of the different metal nanoparticle sheets realizes more flexible plasmonic color tuning.

  15. Molecularly stabilised ultrasmall gold nanoparticles: synthesis, characterization and bioactivity.

    Science.gov (United States)

    Leifert, Annika; Pan-Bartnek, Yu; Simon, Ulrich; Jahnen-Dechent, Willi

    2013-07-21

    Gold nanoparticles (AuNPs) are widely used as contrast agents in electron microscopy as well as for diagnostic tests. Due to their unique optical and electrical properties and their small size, there is also a growing field of potential applications in medical fields of imaging and therapy, for example as drug carriers or as active compounds in thermotherapy. Besides their intrinsic optical properties, facile surface decoration with (bio)functional ligands renders AuNPs ideally suited for many industrial and medical applications. However, novel AuNPs may have toxicological profiles differing from bulk and therefore a thorough analysis of the quantitative structure-activity relationship (QSAR) is required. Several mechanisms are proposed that cause adverse effects of nanoparticles in biological systems. Catalytic generation of reactive species due to the large and chemically active surface area of nanomaterials is well established. Because nanoparticles approach the size of biological molecules and subcellular structures, they may overcome natural barriers by active or passive uptake. Ultrasmall AuNPs with sizes of 2 nm or less may even behave as molecular ligands. These types of potential interactions would imply a size and ligand-dependent behaviour of any nanomaterial towards biological systems. Thus, to fully understand their QSAR, AuNPs bioactivity should be analysed in biological systems of increasing complexity ranging from cell culture to whole animal studies.

  16. Molecularly stabilised ultrasmall gold nanoparticles: synthesis, characterization and bioactivity

    Science.gov (United States)

    Leifert, Annika; Pan-Bartnek, Yu; Simon, Ulrich; Jahnen-Dechent, Willi

    2013-06-01

    Gold nanoparticles (AuNPs) are widely used as contrast agents in electron microscopy as well as for diagnostic tests. Due to their unique optical and electrical properties and their small size, there is also a growing field of potential applications in medical fields of imaging and therapy, for example as drug carriers or as active compounds in thermotherapy. Besides their intrinsic optical properties, facile surface decoration with (bio)functional ligands renders AuNPs ideally suited for many industrial and medical applications. However, novel AuNPs may have toxicological profiles differing from bulk and therefore a thorough analysis of the quantitative structure-activity relationship (QSAR) is required. Several mechanisms are proposed that cause adverse effects of nanoparticles in biological systems. Catalytic generation of reactive species due to the large and chemically active surface area of nanomaterials is well established. Because nanoparticles approach the size of biological molecules and subcellular structures, they may overcome natural barriers by active or passive uptake. Ultrasmall AuNPs with sizes of 2 nm or less may even behave as molecular ligands. These types of potential interactions would imply a size and ligand-dependent behaviour of any nanomaterial towards biological systems. Thus, to fully understand their QSAR, AuNPs bioactivity should be analysed in biological systems of increasing complexity ranging from cell culture to whole animal studies.

  17. Synthesis of gold and silver nanoparticles using Mukia maderaspatna plant extract and its anticancer activity.

    Science.gov (United States)

    Devi, Guruviah Karthiga; Sathishkumar, Kannaiyan

    2017-03-01

    The present investigation reveals the in vitro cytotoxic effect of the biosynthesised metal nanoparticles on the MCF 7 breast cancer cell lines. The gold and silver nanoparticles were synthesised through an environmentally admissible route using the Mukia Maderaspatna plant extract. Initially, the biomolecules present in the plant extract were analysed using phytochemical analysis. Further, these biomolecules reduce the metal ion solution resulting from the formation of metal nanoparticles. The reaction parameters were optimised to control the size of nanoparticles which were confirmed by UV visible spectroscopy. Various instrumental techniques such as Fourier transform-infrared spectroscopy, high resolution transmission electron microscopy, energy dispersive X-ray and scanning electron microscopy were employed to characterise the synthesised gold and silver nanoparticles. The synthesised gold and silver nanoparticles were found to be 20-50 nm and were of different shapes including spherical, triangle and hexagonal. MTT and dual staining assays were carried out with different concentrations (1, 10, 25, 50 and 100 µg/ml) of gold and silver nanoparticles. The results show that the nanoparticles exhibited significant cytotoxic effects with IC 50 value of 44.8 µg/g for gold nanoparticles and 51.3 µg/g for silver nanoparticles. The observations in this study show that this can be developed as a promising nanomaterial in pharmaceutical and healthcare sector.

  18. Green Synthesis of Gold and Silver Nanoparticles Using Averrhoa bilimbi Fruit Extract

    Directory of Open Access Journals (Sweden)

    R. S. Rimal Isaac

    2013-01-01

    Full Text Available We report on rapid one-step green synthesis of gold and silver nanoparticles using fruit extract of Averrhoa bilimbi Linn. UV-Vis absorption spectroscopy was used to monitor the quantitative formation of gold and silver nanoparticles. The characteristics of the obtained gold and silver nanoparticles were studied using UV-Vis absorption spectroscopy (UV/Vis, Fourier transform infrared spectroscopy (FTIR, Scanning electron microscopy (SEM, and Energy-dispersive spectroscopy (EDX. UV/Vis spectrum showed Surface Plasmon Resonance (SPR for both gold and silver nanoparticles at 540 and 420 nm. The EDX spectrum of the solution containing gold and silver nanoparticles confirmed the presence of elemental gold and silver signals. The average diameter of the prepared nanoparticles in solution was about 50–150 nm. Synthesized particles were either hexagonal or rhomboidal in shape. This synthesis approach of gold and silver nanoparticles is cost effective and can be widely used in biological systems. The effect of fruit extract and metal ion concentration was also studied.

  19. Size-dependent radiosensitization of PEG-coated gold nanoparticles for cancer radiation therapy

    CERN Document Server

    Zhang, Xiao-Dong; Shen, Xiu; Chen, Jie; Sun, Yuan-Ming; Liu, Pei-Xun; Liang, Xing-Jie

    2012-01-01

    Gold nanoparticles have been conceived as a radiosensitizer in cancer radiation therapy, but one of the important questions for primary drug screening is what size of gold nanoparticles can optimally enhance radiation effects. Herein, we perform in vitro and in vivo radiosensitization studies of 4.8, 12.1, 27.3, and 46.6 nm PEG-coated gold nanoparticles. In vitro results show that all sizes of the PEG-coated gold nanoparticles can cause a significant decrease in cancer cell survival after gamma radiation. 12.1 and 27.3 nm PEG-coated gold nanoparticles have dispersive distributions in the cells and have stronger sensitization effects than 4.8 and 46.6 nm particles by both cell apoptosis and necrosis. Further, in vivo results also show all sizes of the PEG-coated gold nanoparticles can decrease tumor volume and weight after 5 Gy radiations, and 12.1 and 27.3 nm PEG-coated gold nanoparticles have greater sensitization effects than 4.8 and 46.6 nm particles, which can lead to almost complete disappearance of the ...

  20. Phase transfer of citrate stabilized gold nanoparticles using nonspecifically adsorbed polymers.

    Science.gov (United States)

    Alkilany, Alaaldin M; Caravana, Aidan C; Hamaly, Majd A; Lerner, Kevin T; Thompson, Lucas B

    2016-01-01

    Many synthetic approaches for gold nanoparticles rely on an aqueous media, resulting in water-soluble nanoparticles, which limits the ability to incorporate gold nanoparticles into other organic solvents or hydrophobic polymeric composites. Surface functionalization and phase transfer approaches using alkylthiols or alkylamines, which strongly bind the gold surface, are common routes to overcome this limitation, however they are typically challenging methods. In this paper we report an approach to transport citrate capped gold nanoparticles into a variety of solvents, including ones that are hydrophobic and not miscible with water without the need for phase transfer agents. We suspend gold nanoparticles in a water-miscible polar organic solvent that also is a solvent for a hydrophobic polymer. After drying, polymer-stabilized gold nanoparticles were found to be dispersible in various hydrophobic solvents with maintained colloidal stability. This work investigates two hydrophobic polymers, namely (polymethylmethacrylate and polyvinylacetate), which share common chemical motifs but have significantly different physiochemical properties. Interestingly, a significant difference in their ability to stabilize the transferred gold nanoparticles is observed and discussed.

  1. Study on the interaction between gold nanoparticles and papain by spectroscopic methods

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Gongke; Chen, Ye; Yan, Changling; Lu, Yan, E-mail: yanlu2001@sohu.com

    2015-01-15

    The interaction between gold nanoparticles and papain was studied by fluorescence, UV–vis absorption and synchronous fluorescence spectroscopic techniques under the physiological conditions. The results showed that the binding of gold nanoparticles to papain was a spontaneous binding process. The fluorescence of papain was strongly quenched by gold nanoparticles. The quenching mechanism was probably a static quenching type with the formation of a ground state complex. The Stern–Volmer quenching constants, the binding constants and the number of binding sites in different temperatures were calculated. The corresponding thermodynamic parameters ΔH,ΔS and ΔG indicated that hydrogen bonding and Van der Waals forces played a key role in the interaction process. Additionally, the conformational change of papain induced by gold nanoparticles was analyzed by UV–vis absorption and synchronous fluorescence spectra. - Highlights: • Spherical and monodispersed gold nanoparticles are synthesized. • The fluorescence of papain is quenched by gold nanoparticles under physiological conditions. • Hydrogen bonding and Van der Waals forces may play an essential role in the binding of gold nanoparticles with papain. • This binding interaction is predominantly enthalpy driven.

  2. A proposed mechanism of the influence of gold nanoparticles on DNA hybridization.

    Science.gov (United States)

    Sedighi, Abootaleb; Li, Paul C H; Pekcevik, Idah C; Gates, Byron D

    2014-07-22

    A combination of gold nanoparticles (AuNPs) and nucleic acids has been used in biosensing applications. However, there is a poor fundamental understanding of how gold nanoparticle surfaces influence the DNA hybridization process. Here, we measured the rate constants of the hybridization and dehybridization of DNA on gold nanoparticle surfaces to enable the determination of activation parameters using transition state theory. We show that the target bases need to be detached from the gold nanoparticle surfaces before zipping. This causes a shift of the rate-limiting step of hybridization to the mismatch-sensitive zipping step. Furthermore, our results propose that the binding of gold nanoparticles to the single-stranded DNA segments (commonly known as bubbles) in the duplex DNA stabilizes the bubbles and accelerates the dehybridization process. We employ the proposed mechanism of DNA hybridization/dehybridization to explain the ability of 5 nm diameter gold nanoparticles to help discriminate between single base-pair mismatched DNA molecules when performed in a NanoBioArray chip. The mechanistic insight into the DNA-gold nanoparticle hybridization/dehybridization process should lead to the development of new biosensors.

  3. Mesoporous silica nanoparticles with tunable pore size for tailored gold nanoparticles

    Science.gov (United States)

    Sponchia, G.; Marin, R.; Freris, I.; Marchiori, M.; Moretti, E.; Storaro, L.; Canton, P.; Lausi, A.; Benedetti, A.; Riello, P.

    2014-02-01

    The aim of this paper was to verify a possible correlation between the pore-size of mesoporous silica nanoparticles (MSNs) and the sizes of gold nanoparticles (AuNPs) obtained by an impregnation of gold(III) chloride hydrate solution in the MSNs, followed by a specific thermal treatment. Mesoporous silica nanoparticles with tunable pore diameter were synthesized via a surfactant-assisted method. Tetraethoxysilane as silica precursor, cetyltrimethylammonium bromide (CTAB) as surfactant and toluene as swelling agent were used. By varying the CTAB-toluene molar ratio, the average dimension of the pores could be tuned from 2.8 to 5.5 nm. Successively, thiol groups were grafted on the surface of the MSNs. Finally, the thermal evolution of the gold salt, followed by "in situ" X-ray powder diffraction (XRPD) and thermogravimetric analysis (TGA), revealed an evident correlation among the degradation of the thiol groups, the pore dimension of the MSNs and the size of the AuNPs. The samples were characterized by means of nitrogen adsorption-desorption, transmission electron microscopy, small-angle X-ray scattering, XRPD "in situ" by synchrotron radiation, and "ex situ" by conventional techniques, diffuse reflectance infrared Fourier transform spectroscopy, and TGA.

  4. Phytogenic silver, gold, and bimetallic nanoparticles as novel antitubercular agents

    Directory of Open Access Journals (Sweden)

    Singh R

    2016-05-01

    Full Text Available Richa Singh,1 Laxman Nawale,2 Manisha Arkile,2 Sweety Wadhwani,1 Utkarsha Shedbalkar,1 Snehal Chopade,1 Dhiman Sarkar,2 Balu Ananda Chopade1,3 1Department of Microbiology, Savitribai Phule Pune University, 2Combichem-Bioresource Center, Organic Chemistry Division, National Chemical Laboratory, Pune, 3Dr Babasaheb Ambedkar Marathwada University, Aurangabad, Maharashtra, India Purpose: Multi- and extensively drug-resistant tuberculosis (TB is a global threat to human health. It requires immediate action to seek new antitubercular compounds and devise alternate strategies. Nanomaterials, in the present scenario, have opened new avenues in medicine, diagnosis, and therapeutics. In view of this, the current study aims to determine the efficacy of phytogenic metal nanoparticles to inhibit mycobacteria. Methods: Silver (AgNPs, gold (AuNPs, and gold–silver bimetallic (Au–AgNPs nanoparticles synthesized from medicinal plants, such as Barleria prionitis, Plumbago zeylanica, and Syzygium cumini, were tested against Mycobacterium tuberculosis and M. bovis BCG. In vitro and ex vivo macrophage infection model assays were designed to determine minimum inhibitory concentration (MIC and half maximal inhibitory concentration of nanoparticles. Microscopic analyses were carried out to demonstrate intracellular uptake of nanoparticles in macrophages. Besides this, biocompatibility, specificity, and selectivity of nanoparticles were also established with respect to human cell lines. Results: Au–AgNPs exhibited highest antitubercular activity, with MIC of <2.56 µg/mL, followed by AgNPs. AuNPs did not show such activity at concentrations of up to 100 µg/mL. In vitro and ex vivo macrophage infection model assays revealed the inhibition of both active and dormant stage mycobacteria on exposure to Au–AgNPs. These nanoparticles were capable of entering macrophage cells and exhibited up to 45% cytotoxicity at 30 µg/mL (ten times MIC concentration after 48 hours

  5. Anthelmintic efficacy of gold nanoparticles derived from a phytopathogenic fungus, Nigrospora oryzae.

    Directory of Open Access Journals (Sweden)

    Pradip Kumar Kar

    Full Text Available Exploring a green chemistry approach, this study brings to the fore, the anthelmintic efficacy of gold nanoparticles, highlighting the plausible usage of myconanotechnology. Gold nanoparticles of ∼6 to ∼18 nm diameter were synthesized by treating the mycelia-free culture filtrate of the phytopathogenic fungus with gold chloride. Their size and morphology were confirmed by UV-Vis spectroscopy, DLS data, AFM and TEM images. The XRD studies reveal a crystalline nature of the nanoparticles, which are in cubic phase. The FTIR spectroscopic studies before and after the formation of nanoparticles show the presence of possible functional groups responsible for the bio-reduction and capping of the synthesized gold nanoparticles. The latter were tested as vermifugal agents against a model cestode Raillietina sp., an intestinal parasite of domestic fowl. Further, ultrastructural and biochemical parameters were used to corroborate the efficacy study.

  6. Optical sorting of gold nanoparticles based on the red-shift of plasmon resonance

    Science.gov (United States)

    Ploschner, Martin; Čižmar, Tomáš; Mazilu, Michael; Di Falco, Andrea; Dholakia, Kishan

    2012-10-01

    We present an experimental technique allowing size-based all-optical sorting of gold nanoparticles. The technique is based on the red-shift of plasmon resonance, due to retardation effects, with increasing particle size. As a result, smaller gold nanoparticles are influenced strongly by shorter wavelengths whereas larger gold nanoparticles are influenced more strongly by longer wavelengths. We utilise this retardation effect and realize sorting in a system of two counter-propagating evanescent waves, each at different wavelengths that selectively guide nanoparticles of different sizes in opposite directions. We validate this concept by demonstrating bidirectional sorting of gold nanoparticles of either 150 or 130 nm in diameter from those of 100 nm in diameter within a mixture.

  7. Durable PROX catalyst based on gold nanoparticles and hydrophobic silica

    KAUST Repository

    Laveille, Paco

    2016-01-20

    3 nm gold nanoparticles (Au NP) obtained by direct chemical reduction of AuPPh3Cl in the presence of methyl-terminated silica exhibit superior durability for low temperature CO oxidation in the presence of hydrogen (PROX). The activity of hydrophobic Au/SiO2-R972 indeed appears much more stable with time-on-stream than those of the OH-terminated, hydrophilic Au/TiO2 and Au/Al2O3 catalysts, with similar Au NP size. This enhanced stability is attributed to the peculiar catalyst surface of Au/SiO2-R972. Not only may the support hydrophobicity concentrate and facilitate reactant adsorption and product desorption over Au NP, but methyl-terminated SiO2-R972 likely also inhibits carbonatation of the Au/support interface. Hence, at a temperature at which H2/H2O “cleaning” of the carbonate-contaminated Au/Al2O3 and Au/TiO2 surface is inefficient (< 100°C), passivated Au/SiO2-R972 displays much more stable PROX activity. Besides, the virtual absence of surface hydroxyl groups, which provide sites for water formation in H2/O2 atmospheres, can also account for the improved PROX selectivity (>85%) observed over Au/SiO2-R972. This new example, of CO oxidation activity of gold nanoparticles dispersed over a hydrophobic, “inert” support, clearly emphasizes the role of hydrogen as a promoter for the gold-catalyzed oxidation of CO at low temperature. Unlike support-mediated oxygen activation, hydrogen-only mediated oxygen activation takes full advantage of the hydrophobic surface, which is much more resistant against CO2 and thus remains free of poisonous carbonate species, as compared with hydroxyl-terminated catalysts. Hence, although the absence of surface hydroxyl groups prevents the hydrophobic Au/SiO2-R972 catalyst to reach the state-of-the-art activities initially displayed by Au/TiO2 and Au/Al2O3, it brings long-term stability with time-on-stream and superior selectivity, which opens up promising perspectives in the development of viable PROX catalysts based on gold.

  8. Flow field-flow fractionation: a versatile approach for size characterization of alpha-tocopherol-induced enlargement of gold nanoparticles.

    Science.gov (United States)

    Sermsri, Wimut; Jarujamrus, Purim; Shiowatana, Juwadee; Siripinyanond, Atitaya

    2010-04-01

    Flow field-flow fractionation (FlFFF) was used for size characterization of gold nanoparticles. The measured particle sizes obtained from FlFFF for the commercial 10 nm gold nanoparticle standard and the gold nanoparticles synthesized in the laboratory were in good agreement with those measured by transmission electron microscopy (TEM). Further, the capability of alpha-tocopherol to induce enlargement of gold nanoparticles by catalysis of the reduction of AuCl(4)(-) by citrate was observed by monitoring the changes in particle size of gold nanoparticles using FlFFF. The effects of alpha-tocopherol and incubation time on enlargement of the gold nanoparticles were examined. Higher concentrations of alpha-tocopherol resulted in larger nanoparticles. At fixed alpha-tocopherol concentration, larger nanoparticles were formed at longer incubation times.

  9. Chrysopogon zizanioides aqueous extract mediated synthesis characterization of crystalline silver and gold nanoparticles for biomedical applications

    Directory of Open Access Journals (Sweden)

    Arunachalam KD

    2013-07-01

    Full Text Available Kantha D Arunachalam, Sathesh Kumar Annamalai Center for Environmental Nuclear Research, Directorate of Research, SRM University, Chennai, Tamil Nadu, India Abstract: The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology as it does not involve any harmful chemicals. The aim of this study was to develop a simple biological method for the synthesis of silver and gold nanoparticles using Chrysopogon zizanioides. To exploit various plant materials for the biosynthesis of nanoparticles was considered a green technology. An aqueous leaf extract of C. zizanioides was used to synthesize silver and gold nanoparticles by the bioreduction of silver nitrate (AgNO3 and chloroauric acid (HAuCl4 respectively. Water-soluble organics present in the plant materials were mainly responsible for reducing silver or gold ions to nanosized Ag or Au particles. The synthesized silver and gold nanoparticles were characterized by ultraviolet (UV-visible spectroscopy, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDAX, Fourier transform infrared spectroscopy (FTIR, and X-ray diffraction (XRD analysis. The kinetics decline reactions of aqueous silver/gold ion with the C. zizanioides crude extract were determined by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to the extract were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. This eco-friendly approach for the synthesis of nanoparticles is simple, can be scaled up for large-scale production with powerful bioactivity as demonstrated by the synthesized silver nanoparticles. The synthesized nanoparticles can have clinical use as antibacterial, antioxidant, as well as cytotoxic agents and can be used for biomedical applications. Keywords: nanoparticles, bioreduction, SEM, silver, gold

  10. Gold core@silver semishell Janus nanoparticles prepared by interfacial etching

    Science.gov (United States)

    Chen, Limei; Deming, Christopher P.; Peng, Yi; Hu, Peiguang; Stofan, Jake; Chen, Shaowei

    2016-07-01

    Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold cores, as manifested in transmission electron microscopy, UV-vis absorption, and X-ray photoelectron spectroscopy measurements. Interestingly, the Au@Ag semishell Janus nanoparticles exhibited enhanced electrocatalytic activity in oxygen reduction reactions, as compared to their Au@Ag and Ag@Au core-shell counterparts, likely due to a synergistic effect between the gold cores and silver semishells that optimized oxygen binding to the nanoparticle surface.Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold

  11. Electrochemical extraction of gold from wastes as nanoparticles stabilized by phospholipids.

    Science.gov (United States)

    Moriwaki, Hiroshi; Yamada, Kotaro; Usami, Hisanao

    2017-02-01

    A simple one-step method for the extraction of gold from wastes as nanoparticles stabilized by phospholipids is demonstrated. This is achieved by applying an AC voltage for 5s to the gold-containing wastes, which act as the electrodes in a buffer solution containing a dispersed phospholipid (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC). This is an environmentally friendly and rapid method for recovering gold from wastes. The extracted gold nanoparticles have significant potential as a catalyst or biomedical material. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Application of gold nanoparticles to x-ray diagnostics and photothermal therapy of cancer

    Science.gov (United States)

    Terentyuk, G. S.; Maksimova, I. L.; Tuchin, V. V.; Zharov, V. P.; Khlebtsov, B. N.; Bogatyrev, V. A.; Dykman, L. A.; Khlebtsov, N. G.

    2007-06-01

    We describe applications of colloidal gold nanoparticles and silica/gold nanoshells to photothermal therapy and X-ray diagnostics of cancer exemplified by spontaneous tumor of cats and dog. It is shown that the contrast of X-ray images of a cat mammalian tumor can be increased significantly by injection of 3-5-nm gold nanoparticles. We also present preliminary results of a complex approach to treatment a dog mouth cavity melanoma by using immunotherapy together with laser photothermolysis enhanced with silica/gold nanoshells.

  13. Antibacterial nanocarriers of resveratrol with gold and silver nanoparticles.

    Science.gov (United States)

    Park, Sohyun; Cha, Song-Hyun; Cho, Inyoung; Park, Soomin; Park, Yohan; Cho, Seonho; Park, Youmie

    2016-01-01

    This study focused on the preparation of resveratrol nanocarrier systems and the evaluation of their in vitro antibacterial activities. Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) for resveratrol nanocarrier systems were synthesized using green synthetic routes. During the synthesis steps, resveratrol was utilized as a reducing agent to chemically reduce gold and silver ions to AuNPs and AgNPs. This system provides green and eco-friendly synthesis routes that do not involve additional chemical reducing agents. Resveratrol nanocarriers with AuNPs (Res-AuNPs) and AgNPs (Res-AgNPs) were observed to be spherical and to exhibit characteristic surface plasmon resonance at 547 nm and at 412-417 nm, respectively. The mean size of the nanoparticles ranged from 8.32 to 21.84 nm, as determined by high-resolution transmission electron microscopy. The face-centered cubic structure of the Res-AuNPs was confirmed by high-resolution X-ray diffraction. Fourier-transform infrared spectra indicated that the hydroxyl groups and C=C in the aromatic ring of resveratrol were involved in the reduction reaction. Res-AuNPs retained excellent colloidal stability during ultracentrifugation and re-dispersion, suggesting that resveratrol also played a role as a capping agent. Zeta potentials of Res-AuNPs and Res-AgNPs were in the range of -20.58 to -48.54 mV. Generally, against Gram-positive and Gram-negative bacteria, the Res-AuNPs and Res-AgNPs exhibited greater antibacterial activity compared to that of resveratrol alone. Among the tested strains, the highest antibacterial activity of the Res-AuNPs was observed against Streptococcus pneumoniae. The addition of sodium dodecyl sulfate during the synthesis of Res-AgNPs slightly increased their antibacterial activity. These results suggest that the newly developed resveratrol nanocarrier systems with metallic nanoparticles show potential for application as nano-antibacterial agents with enhanced activities.

  14. Enhanced Antimicrobial and Anticancer Activity of Silver and Gold Nanoparticles Synthesised Using Sargassum incisifolium Aqueous Extracts.

    Science.gov (United States)

    Mmola, Mokone; Roes-Hill, Marilize Le; Durrell, Kim; Bolton, John J; Sibuyi, Nicole; Meyer, Mervin E; Beukes, Denzil R; Antunes, Edith

    2016-12-02

    A detailed, methodical approach was used to synthesise silver and gold nanoparticles using two differently prepared aqueous extracts of the brown algae Sargassum incisifolium. The efficiency of the extracts in producing nanoparticles were compared to commercially available brown algal fucoidans, a major constituent of brown algal aqueous extracts. The nanoparticles were characterised using TEM, XRD and UV/Vis spectroscopy and zeta potential measurements. The rate of nanoparticle formation was assessed using UV/Vis spectroscopy and related to the size, shape and morphology of the nanoparticles as revealed by TEM. The antioxidant, reducing power and total polyphenolic contents of the aqueous extracts and fucoidans were determined, revealing that the aqueous extracts with the highest contents produced smaller, spherical, more monodisperse nanoparticles at a faster rate. The nanoparticles were assessed against two gram-negative bacteria, two gram-positive bacteria and one yeast strain. In contrast to the literature, the silver nanoparticles produced using the aqueous extracts were particularly toxic to Gram-negative bacteria, while the gold nanoparticles lacked activity. The cytotoxic activity of the nanoparticles was also evaluated against cancerous (HT-29, MCF-7) and non-cancerous (MCF-12a) cell lines. The silver nanoparticles displayed selectivity, since the MCF-12a cell line was found to be resistant to the nanoparticles, while the cancerous HT-29 cell line was found to be sensitive (10% viability). The gold nanoparticles displayed negligible toxicity.

  15. In Situ Synthesis and Deposition of Gold Nanoparticles with Different Morphologies on Glass and ITO Substrate by Ultrasonic Spray Pyrolysis

    OpenAIRE

    María de la Garza; Israel López; Idalia Gómez

    2013-01-01

    Gold nanoparticles were synthesized and deposited in situ by ultrasonic spray pyrolysis on glass and indium tin oxide (ITO) substrates. This technique led to the formation of gold nanoparticles with different morphologies without the use of any capping agent. The gold nanoparticles deposited on glass substrate were obtained as nanospheres with an average particle size of 30 nm with some agglomerates; however, the nanoparticles deposited on ITO substrate were obtained with different morphologi...

  16. Gold nanoparticle-coated biomaterial as SERS micro-probes

    Indian Academy of Sciences (India)

    G V Pavan Kumar

    2011-06-01

    We report for the first time, on the utility of plant-based biomaterial as enhanced-Raman scattering probes. The bio-substrate used in this study are commonly found in plant extracts, and are cost-effective, mechanically robust, flexible and easily transportable. The probe was fabricated by coating the plant extract with gold nanoparticles and characterized. By employing a ‘single-touch contact’ method, we reveal the ability of these probes to detect routinely used Raman markers such as 2-napthalenethiol and rhodamine B, at nano-molar concentrations, in dry and liquid forms, respectively. Reproducibility of the signals with variation <5%, and the ability to detect biomolecules are demonstrated herein. We envision these bio-probes as potential candidates for enhanced Raman sensing in chemical, environmental, and archaeological applications. By further engineering the shape, morphology, and surface chemistry of these micro-probes, we foresee their utility as miniaturized, natural SERS substrates.

  17. Self-organization of gold nanoparticles on silanated surfaces

    Directory of Open Access Journals (Sweden)

    Htet H. Kyaw

    2015-12-01

    Full Text Available The self-organization of monolayer gold nanoparticles (AuNPs on 3-aminopropyltriethoxysilane (APTES-functionalized glass substrate is reported. The orientation of APTES molecules on glass substrates plays an important role in the interaction between AuNPs and APTES molecules on the glass substrates. Different orientations of APTES affect the self-organization of AuNps on APTES-functionalized glass substrates. The as grown monolayers and films annealed in ultrahigh vacuum and air (600 °C were studied by water contact angle measurements, atomic force microscopy, X-ray photoelectron spectroscopy, UV–visible spectroscopy and ultraviolet photoelectron spectroscopy. Results of this study are fundamentally important and also can be applied for designing and modelling of surface plasmon resonance based sensor applications.

  18. Cyclodextrin-Based [1]Rotaxanes on Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yanli Zhao

    2012-08-01

    Full Text Available Transformation of mechanically interlocked molecules (e.g., rotaxanes and catenanes into nanoscale materials or devices is an important step towards their real applications. In our current work, an azobenzene-modified β-cyclodextrin (β-CD derivative that can form a self-inclusion complex in aqueous solution was prepared. The self-included β-CD derivative was then functionalized onto a gold nanoparticle (AuNP surface via a ligand-exchange reaction in aqueous solution, leading to the formation of AuNP-[1]rotaxane hybrids. Corresponding non-self-included β-CD derivative functionalized AuNPs were also developed in a DMF/H2O mixture solution for control experiments. These hybrids were fully characterized by UV-vis and circular dichroism spectroscopies, together with transmission electron microscopy (TEM. The competitive binding behavior of the hybrids with an adamantane dimer was investigated.

  19. Gold Nanoparticles and Nanocomposites in Clinical Diagnostics Using Electrochemical Methods

    Directory of Open Access Journals (Sweden)

    Pranjal Chandra

    2013-01-01

    Full Text Available Progress and development in clinical diagnostics certainly focus upon the advances in the nanomaterials, particularly gold nanoparticles (AuNPs that offer promise to solve the biocompatible and sensitive detection systems. This paper focuses on the recent application of AuNPs in clinical diagnosis. Various important methods of AuNPs synthesis and their application in clinical detection of various biomolecules using electrochemical detection methods have been described. AuNPs alone and in various composites are also described based on the various biosensors design recently published for the detection of cancer biomarkers, proteins, bacteria, and cancer cells. The effect of AuNPs type and size in clinical detection has also been briefly illustrated.

  20. Self-organization of gold nanoparticles on silanated surfaces.

    Science.gov (United States)

    Kyaw, Htet H; Al-Harthi, Salim H; Sellai, Azzouz; Dutta, Joydeep

    2015-01-01

    The self-organization of monolayer gold nanoparticles (AuNPs) on 3-aminopropyltriethoxysilane (APTES)-functionalized glass substrate is reported. The orientation of APTES molecules on glass substrates plays an important role in the interaction between AuNPs and APTES molecules on the glass substrates. Different orientations of APTES affect the self-organization of AuNps on APTES-functionalized glass substrates. The as grown monolayers and films annealed in ultrahigh vacuum and air (600 °C) were studied by water contact angle measurements, atomic force microscopy, X-ray photoelectron spectroscopy, UV-visible spectroscopy and ultraviolet photoelectron spectroscopy. Results of this study are fundamentally important and also can be applied for designing and modelling of surface plasmon resonance based sensor applications.

  1. Enhanced Photoluminescence Property for Quantum Dot-Gold Nanoparticle Hybrid

    Science.gov (United States)

    Huang, Qianqian; Chen, Jing; Zhao, Jian; Pan, Jiangyong; Lei, Wei; Zhang, Zichen

    2015-10-01

    In this paper, we have synthesized ZnCdSeS quantum dots (QDs)-gold nanoparticle (Au NPs) hybrids in aqueous solution via bi-functional linker mercaptoacetic acid (MPA). The absorption peaks of ZnCdSeS QDs and Au are both located at 520 nm. It is investigated that PL intensity of QD-Au hybrid can be affected by the amounts of Au and pH value of hybrid solution. The located surface plasmon resonance (LSPR) effect of QD-Au NPs has been demonstrated by increased fluorescence intensity. The phenomenon of fluorescence enhancement can be maximized under the optimized pH value of 8.5. LSPR-enhanced photoluminescence property of QD-Au hybrid will be beneficial for the potential applications in the area of biological imaging and detection.

  2. Detection of Lectins by Saccharide-gold Nanoparticle Conjugates

    Institute of Scientific and Technical Information of China (English)

    HOU Qiong; WANG Jin-e; LIU Xia; LI Xiao-kun; MA Li-na; DUAN Wu-biao; WANG Zhen-xin

    2012-01-01

    A general functionalization strategy was reported,which enables one to conjugate saccharide(SA) on gold nanoparticle(GNP) surface without affecting SA properties.First,disulfide phenylboronic acid(Bor) functionalized GNPs(Bor@GNPs) were synthesized by the reaction of citrate stabilized GNPs of 13 nm in diameter with the mixture of Bor and pentapeptide(Cys-Ala-Leu-Asn-Asn,CALNN).Subsequently,the SA-GNP conjugates(SA@GNPs) were prepared by coupling SA to the GNP surface via the reaction of phenylboronic acid(PBA) with the cis-diol configuration in SA.The interactions of three SA@GNPs with three lectins have been analyzed by UV-visible spectroscopic and transmission electronic microscopic(TEM) techniques,respectively.The experimental results demonstrate that SA@GNPs can efficiently bind to lectins and show a great promise as optical probes for monitoring specific affinities of lectins for SA,and detecting lectins with high sensitivity.

  3. Electron microscopy of gold nanoparticles at atomic resolution

    Science.gov (United States)

    Azubel, Maia; Koivisto, Jaakko; Malola, Sami; Bushnell, David; Hura, Greg L.; Koh, Ai Leen; Tsunoyama, Hironori; Tsukuda, Tatsuya; Pettersson, Mika; Häkkinen, Hannu; Kornberg, Roger D.

    2014-01-01

    Structure determination of gold nanoparticles (AuNPs) is necessary for understanding their physical and chemical properties, and only one AuNP larger than 1 nm in diameter, an Au102NP, has been solved to atomic resolution. Whereas the Au102NP structure was determined by X-ray crystallography, other large AuNPs have proved refractory to this approach. Here we report the structure determination of an Au68NP at atomic resolution by aberration-corrected transmission electron microscopy (AC-TEM), performed with the use of a minimal electron dose, an approach that should prove applicable to metal NPs in general. The structure of the Au68NP was supported by small angle X-ray scattering (SAXS) and by comparison of observed infrared (IR) absorption spectra with calculations by density functional theory (DFT). PMID:25146285

  4. Targeting and molecular imaging of HepG2 cells using surface-functionalized gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rathinaraj, Pierson [Auckland University of Technology, Institute of Biomedical Technologies (New Zealand); Lee, Kyubae; Choi, Yuri; Park, Soo-Young [Kyungpook National University, School of Applied Chemical Engineering, Graduate School (Korea, Republic of); Kwon, Oh Hyeong [Kumoh National Institute of Technology, Department of Polymer Science and Engineering (Korea, Republic of); Kang, Inn-Kyu, E-mail: ikkang@knu.ac.kr [Kyungpook National University, School of Applied Chemical Engineering, Graduate School (Korea, Republic of)

    2015-07-15

    Mercaptosuccinic acid (M)-conjugated gold nanoparticles (GM) were prepared and characterized by transmission electron microscope and dynamic light scattering. M was used to improve the monodispersity and non-specific intracellular uptake of nanoparticles. Lactobionic acid (L) was subsequently conjugated to the GM to target preferentially HepG2 cells (liver cancer cells) that express asialoglycoprotein receptors (ASGPR) on their membrane surfaces and facilitate the transit of nanoparticles across the cell membrane. The mean size of lactobionic acid-conjugated gold nanoparticle (GL) was approximately 10 ± 0.2 nm. Finally, the Atto 680 dye (A6) was coupled to the nanoparticles to visualize their internalization into HepG2 cells. The interaction of surface-modified gold nanoparticles with HepG2 cells was studied after culturing cells in media containing the GM or L-conjugated GM (GL)

  5. Green synthesis of well-dispersed gold nanoparticles using Macrotyloma uniflorum.

    Science.gov (United States)

    Aromal, S Aswathy; Vidhu, V K; Philip, Daizy

    2012-01-01

    The synthesis of metal nanoparticles of different sizes, shapes, chemical composition and controlled monodispersity is an important area of research in nanotechnology because of their interesting physical properties and technological applications. Present work describes an eco-friendly method for the synthesis of spherical gold nanoparticles using aqueous extract of Macrotyloma uniflorum. The effects of quantity of extract, temperature and pH on the formation of nanoparticles are studied. The nanoparticles are characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles with fcc phase is evident from HRTEM images, SAED and XRD patterns. Synthesized nanoparticles have size in the range 14-17nm. FTIR spectrum indicates the presence of different functional groups present in the bio-molecule capping the nanoparticles. The possible mechanism leading to the formation of gold nanoparticles is suggested.

  6. Dispersed gold nanoparticles potentially ruin gold barley yellow dwarf virus and eliminate virus infectivity hazards

    Science.gov (United States)

    Alkubaisi, Noorah A.; Aref, Nagwa M. A.

    2017-02-01

    Gold nanoparticles (AuNPs) application melted barley yellow dwarf virus-PAV (BYDV-PAV) spherical nanoparticle capsids. Synergistic therapeutic effects for plant virus resistance were induced by interaction with binding units of prepared AuNPs in a water solution which was characterized and evaluated by zeta sizer, zeta potential and transmission electron microscopy (TEM). The yield of purified nanoparticles of BYDV-PAV was obtained from Hordeum vulgare (Barley) cultivars, local and Giza 121/Justo. It was 0.62 mg/ml from 27.30 g of infected leaves at an A260/A280 ratio. Virus nanoparticle has a spherical shape 30 nm in size by TEM. BYDV-PAV combined with AuNPs to challenge virus function in vivo and in vitro. Dual AuNPs existence in vivo and in vitro affected compacted configuration of viral capsid protein in the interior surface of capsomers, the outer surface, or between the interface of coat protein subunits for 24 and 48 h incubation period in vitro at room temperature. The sizes of AuNPs that had a potentially dramatic deteriorated effect are 3.151 and 31.67 nm with a different intensity of 75.3% for the former and 24.7% for the latter, which enhances optical sensing applications to eliminate virus infectivity. Damages of capsid protein due to AuNPs on the surface of virus subunits caused variable performance in four different types of TEM named puffed, deteriorated and decorated, ruined and vanished. Viral yield showed remarkably high-intensity degree of particle symmetry and uniformity in the local cultivar greater than in Giza 121/Justo cultivar. A high yield of ruined VLPs in the local cultivar than Justo cultivar was noticed. AuNPs indicated complete lysed VLPs and some deteriorated VLPs at 48 h.

  7. Dispersed gold nanoparticles potentially ruin gold barley yellow dwarf virus and eliminate virus infectivity hazards

    Science.gov (United States)

    Alkubaisi, Noorah A.; Aref, Nagwa M. A.

    2016-10-01

    Gold nanoparticles (AuNPs) application melted barley yellow dwarf virus-PAV (BYDV-PAV) spherical nanoparticle capsids. Synergistic therapeutic effects for plant virus resistance were induced by interaction with binding units of prepared AuNPs in a water solution which was characterized and evaluated by zeta sizer, zeta potential and transmission electron microscopy (TEM). The yield of purified nanoparticles of BYDV-PAV was obtained from Hordeum vulgare (Barley) cultivars, local and Giza 121/Justo. It was 0.62 mg/ml from 27.30 g of infected leaves at an A260/A280 ratio. Virus nanoparticle has a spherical shape 30 nm in size by TEM. BYDV-PAV combined with AuNPs to challenge virus function in vivo and in vitro. Dual AuNPs existence in vivo and in vitro affected compacted configuration of viral capsid protein in the interior surface of capsomers, the outer surface, or between the interface of coat protein subunits for 24 and 48 h incubation period in vitro at room temperature. The sizes of AuNPs that had a potentially dramatic deteriorated effect are 3.151 and 31.67 nm with a different intensity of 75.3% for the former and 24.7% for the latter, which enhances optical sensing applications to eliminate virus infectivity. Damages of capsid protein due to AuNPs on the surface of virus subunits caused variable performance in four different types of TEM named puffed, deteriorated and decorated, ruined and vanished. Viral yield showed remarkably high-intensity degree of particle symmetry and uniformity in the local cultivar greater than in Giza 121/Justo cultivar. A high yield of ruined VLPs in the local cultivar than Justo cultivar was noticed. AuNPs indicated complete lysed VLPs and some deteriorated VLPs at 48 h.

  8. Bio-synthesis of gold nanoparticles by human epithelial cells, in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Larios-Rodriguez, E; Rangel-Ayon, C; Herrera-Urbina, R [Departamento de Ingenieria Quimica y Metalurgia, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora, C.P. 83000 (Mexico); Castillo, S J [Departamento de Investigacion en Fisica, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora, C.P. 83000 (Mexico); Zavala, G, E-mail: elarios@polimeros.uson.mx [Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico)

    2011-09-02

    Healthy epithelial cells, in vivo, have the ability to synthesize gold nanoparticles when aqueous tetrachloroauric acid is made to react with human skin. Neither a reducing agent nor a protecting chemical is needed for this bio-synthesis method. The first indication of gold nanoparticle formation is the staining of the skin, which turns deep purple. Stereoscopic optical micrographs of human skin tissue in contact with aqueous tetrachloroauric acid clearly show the staining of the epithelial cells. The UV-Vis spectrum of these epithelial cells shows an absorption band with a maximum at 553 nm. This absorption peak is within the wavelength region where the surface plasmon resonance (SPR) band of aqueous colloidal gold exhibits a maximum. Transmission electron micrographs show that gold nanoparticles synthesized by epithelial cells have sizes between 1 and 100 nm. The electron diffraction pattern of these nanoparticles reveals a crystalline structure whose interplanar distances correspond to fcc metallic gold. Transmission electron micrographs of ultra-thin (70 nm thick) slices of epithelial cells clearly and undoubtedly demonstrate that gold nanoparticles are inside the cell. According to high resolution transmission electron micrographs of intracellular single gold nanoparticles, they have the shape of a polyhedron.

  9. Gold nanoparticles generated in ethosome bilayers, as revealed by cryo-electron-tomography.

    Science.gov (United States)

    de la Presa, Patricia; Rueda, Tatiana; del Puerto Morales, María; Javier Chichón, F; Arranz, Rocío; Valpuesta, José María; Hernando, Antonio

    2009-03-12

    Gold nanoparticles have been synthesized inside ethosomes, vesicles composed of phospholipid, ethanol, and water, which could be very efficient not only in delivery probes to the skin but also as diagnostic and therapeutic multimodal agents. High efficiency encapsulation of gold nanoparticles is achieved by a simple strategy: the nanoparticles synthesis occurs simultaneously with the ethosomes formation in the absence of any undesirable reducing agents. A three-dimensional reconstruction of a gold-embedded ethosome generated by cryoelectron tomography reveals that the gold particle is localized inside the lipid bilayer, leaving the ethosome surface and core free for further functionalization. The resulting gold nanoparticles are homogeneous in size and shape and, depending on synthesis temperature, the size ranges from 10 to 20 nm, as revealed by TEM. The ethosome-nanoparticles hybrids' size has been investigated by means of dynamic light scattering and has been found to vary with temperature and gold salt concentration from 700 to 400 nm. Gold nanoparticles-encapsulated ethosomes offer a versatile platform for the enhancement of pharmacological efficacy in transdermal and dermal delivery systems.

  10. Optic and catalytic properties of gold nanoparticles tuned by homopolymers

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Gold nanoparticles (GNs) are prepared through in situ reduction using NaBH4 in the presence of homopolymer PDMAEMA. The sizes of the GNs can be adjusted by alternating the molar ratio of gold to DMAEMA. Pure PDMAEMA aqueous solution shows a phase-transition at 50℃ at pH 10 and 25℃ at pH 14, while PDMAEMA-supported GNs aqueous solution shows a phase-transition at 47℃ at pH 10 because of the increasing hydrophobic property resulting from GNs. Due to the pH and tempera-ture-responsible characteristics of PDMAEMA, the resulting PDMAEMA-supported GNs exhibit pH adjustable temperature-responsive characteristics in optic and catalytic aspects. Under an acidic condi-tion (pH 2), the GNs show unchanged surface Plasmon absorbance with a peak of 518 nm in a tem-perature range from 20 to 65℃. Under a basic condition (pH 10), the GNs first show the same absorb-ance with a peak at 518 nm in a temperature range from 20 to 40℃, and then the absorbance red shifts from 518 to 545 nm as temperature increases from 40 to 65℃. When the GNs are used as catalysts to catalyze the reduction of p-nitrophenol, the catalytic activity can be adjusted by changing the permeation of reactants in the PDMAEMA layer at low and high temperatures, respectively.

  11. Direct Electrochemistry of Horseradish Peroxidase-Gold Nanoparticles Conjugate

    Directory of Open Access Journals (Sweden)

    Chanchal K. Mitra

    2009-02-01

    Full Text Available We have studied the direct electrochemistry of horseradish peroxidase (HRP coupled to gold nanoparticles (AuNP using electrochemical techniques, which provide some insight in the application of biosensors as tools for diagnostics because HRP is widely used in clinical diagnostics kits. AuNP capped with (i glutathione and (ii lipoic acid was covalently linked to HRP. The immobilized HRP/AuNP conjugate showed characteristic redox peaks at a gold electrode. It displayed good electrocatalytic response to the reduction of H2O2, with good sensitivity and without any electron mediator. The covalent linking of HRP and AuNP did not affect the activity of the enzyme significantly. The response of the electrode towards the different concentrations of H2O2 showed the characteristics of Michaelis Menten enzyme kinetics with an optimum pH between 7.0 to 8.0. The preparation of the sensor involves single layer of enzyme, which can be carried out efficiently and is also highly reproducible when compared to other systems involving the layer-by-layer assembly, adsorption or encapsulation of the enzyme. The immobilized AuNP-HRP can be used for immunosensor applications

  12. Ionic liquid-based stable nanofluids containing gold nanoparticles.

    Science.gov (United States)

    Wang, Baogang; Wang, Xiaobo; Lou, Wenjing; Hao, Jingcheng

    2011-10-01

    A one-phase and/or two-phase method were used to prepare the stable ionic liquid-based nanofluids containing same volume fraction but different sizes or surface states of gold nanoparticles (Au NPs) and their thermal conductivities were investigated in more detail. Five significant experiment parameters, i.e. temperature, dispersion condition, particle size and surface state, and viscosity of base liquid, were evaluated to supply experimental explanations for heat transport mechanisms. The conspicuously temperature-dependent and greatly enhanced thermal conductivity under high temperatures verify that Brownian motion should be one key effect factor in the heat transport processes of ionic liquid-based gold nanofluids. While the positive influences of proper aggregation and the optimized particle size on their thermal conductivity enhancements under some specific conditions demonstrate that clustering may be another critical effect factor in heat transport processes. Moreover, the remarkable difference of the thermal conductivity enhancements of the nanofluids containing Au NPs with different surface states could be attributed to the surface state which has a strong correlation with not only Brownian motion but also clustering. Whilst the close relationship between their thermal conductivity enhancements and the viscosity of base liquid further indicate Brownian motion must occupy the leading position among various influencing factors. Finally, a promisingly synergistic effect of Brownian motion and clustering based on experimental clues and theoretical analyses was first proposed, justifying different mechanisms are sure related. The results may shed lights on comprehensive understanding of heat transport mechanisms in nanofluids.

  13. Using Impedance Measurements to Characterize Surface Modified with Gold Nanoparticles

    Science.gov (United States)

    MacKay, Scott; Abdelrasoul, Gaser N.; Tamura, Marcus; Yan, Zhimin

    2017-01-01

    With the increased practice of preventative healthcare to help reduce costs worldwide, sensor technology improvement is vital to patient care. Point-of-care (POC) diagnostics can reduce time and lower labor in testing, and can effectively avoid transporting costs because of portable designs. Label-free detection allows for greater versatility in the detection of biological molecules. Here, we describe the use of an impedance-based POC biosensor that can detect changes in the surface modification of a micro-fabricated chip using impedance spectroscopy. Gold nanoparticles (GNPs) have been employed to evaluate the sensing ability of our new chip using impedance measurements. Furthermore, we used impedance measurements to monitor surface functionalization progress on the sensor’s interdigitated electrodes (IDEs). Electrodes made from aluminum and gold were employed and the results were analyzed to compare the impact of electrode material. GNPs coated with mercaptoundecanoic acid were also used as a model of biomolecules to greatly enhance chemical affinity to the silicon substrate. The portable sensor can be used as an alternative technology to ELISA (enzyme-linked immunosorbent assays) and polymerase chain reaction (PCR)-based techniques. This system has advantages over PCR and ELISA both in the amount of time required for testing and the ease of use of our sensor. With other techniques, larger, expensive equipment must be utilized in a lab environment, and procedures have to be carried out by trained professionals. The simplicity of our sensor system can lead to an automated and portable sensing system.

  14. Synthesis and antimicrobial activity of gold nanoparticle conjugates with cefotaxime

    Science.gov (United States)

    Titanova, Elena O.; Burygin, Gennady L.

    2016-04-01

    Gold nanoparticles (GNPs) have attracted significant interest as a novel platform for various applications to nanobiotechnology and biomedicine. The conjugates of GNPs with antibiotics and antibodies were also used for selective photothermal killing of protozoa and bacteria. Also the conjugates of some antibiotics with GNPs decreased the number of bacterial growing cells. In this work was made the procedure optimization for conjugation of cefotaxime (a third-generation cephalosporin antibiotic) with GNPs (15 nm) and we examined the antimicrobial properties of this conjugate to bacteria culture of E. coli K-12. Addition of cefotaxime solution to colloidal gold does not change their color and extinction spectrum. For physiologically active concentration of cefotaxime (3 μg/mL), it was shown that the optimum pH for the conjugation was more than 9.5. A partial aggregation of the GNPs in saline medium was observed at pH 6.5-7.5. The optimum concentration of K2CO3 for conjugation cefotaxime with GNPs-15 was 5 mM. The optimum concentration of cefotaxime was at 0.36 μg/mL. We found the inhibition of the growth of E. coli K12 upon application cefotaxime-GNP conjugates.

  15. Gold Nanoparticles in Photonic Crystals Applications: A Review

    Directory of Open Access Journals (Sweden)

    Iole Venditti

    2017-01-01

    Full Text Available This review concerns the recently emerged class of composite colloidal photonic crystals (PCs, in which gold nanoparticles (AuNPs are included in the photonic structure. The use of composites allows achieving a strong modification of the optical properties of photonic crystals by involving the light scattering with electronic excitations of the gold component (surface plasmon resonance, SPR realizing a combination of absorption bands with the diffraction resonances occurring in the body of the photonic crystals. Considering different preparations of composite plasmonic-photonic crystals, based on 3D-PCs in presence of AuNPs, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tunable functionality of these crystals. Several chemical methods for fabrication of opals and inverse opals are presented together with preparations of composites plasmonic-photonic crystals: the influence of SPR on the optical properties of PCs is also discussed. Main applications of this new class of composite materials are illustrated with the aim to offer the reader an overview of the recent advances in this field.

  16. Microreactors for Gold Nanoparticles Synthesis: From Faraday to Flow

    Directory of Open Access Journals (Sweden)

    Md. Taifur Rahman

    2014-06-01

    Full Text Available The seminal work of Michael Faraday in 1850s transmuted the “Alchemy of gold” into a fascinating scientific endeavor over the millennia, particularly in the past half century. Gold nanoparticles (GNPs arguably hold the central position of nanosciences due to their intriguing size-and-shape dependent physicochemical properties, non-toxicity, and ease of functionalization and potential for wide range of applications. The core chemistry involved in the syntheses is essentially not very different from what Michael Faraday resorted to: transforming ions into metallic gold using mild reducing agents. However, the process of such reduction and outcome (shapes and sizes are intricately dependent on basic operational parameters such as sequence of addition and efficiency of mixing of the reagents. Hence, irreproducibility in synthesis and maintaining batch-to-batch quality are major obstacles in this seemingly straightforward process, which poses challenges in scaling-up. Microreactors, by the virtue of excellent control over reagent mixing in space and time within narrow channel networks, opened a new horizon of possibilities to tackle such problems to produce GNPs in more reliable, reproducible and scalable ways. In this review, we will delineate the state-of-the-art of GNPs synthesis using microreactors and will discuss in length how such “flask-to-chip” paradigm shift may revolutionize the very concept of nanosyntheses.

  17. Gold(III) reduction by the rhizobacterium Azospirillum brasilense with the formation of gold nanoparticles.

    Science.gov (United States)

    Tugarova, Anna V; Burov, Andrei M; Burashnikova, Marina M; Kamnev, Alexander A

    2014-01-01

    For the soil nitrogen-fixing bacterium Azospirillum brasilense, the ability to reduce [AuCl4](-) and to form gold nanoparticles (GNPs) has been demonstrated, with the appearance of a mauve tint of the culture. To validate the shapes and chemical nature of nanoparticles, transmission electron microscopy (TEM) and X-ray fluorescence analysis were used. For the widely studied agriculturally important wild-type strains A. brasilense Sp7 and Sp245, GNPs formed after 10 days of incubation of cell biomass with 0.25 mM [AuCl4](-) were shown (using TEM) to be mainly of spherical form (5 to 20 nm in diameter), with rare occasional triangles. In the course of cultivation with [AuCl4](-), after 5 days, a mauve tint was already visible for cells of strain Sp245.5, after 6 days for Sp245 and after 10 days for Sp7. Thus, for the mutant strain Sp245.5 (which has significant differences in the structure and composition of cell-surface polysaccharides as compared with Sp245), a more rapid formation of GNPs was observed. Moreover, their TEM images (also obtained after 10 days) showed different shapes: nano-sized spheres, triangles, hexagons and rods, as well as larger round-shaped flower-like nanoparticles about 100 nm in size. Since by the time of GNP formation in our experiments the cells were found to be already not viable, this confirms the dominating role of cell surface structure and chemical composition in shaping the GNPs formed in the course of [AuCl4](-) reduction to Au(0). This finding may be useful for understanding the natural biogeochemical mechanisms of gold reduction and formation of GNPs involving microorganisms. The data obtained may also help in developing protocols for environmentally friendly synthesis of nanoparticles and possible use of bacterial cells with modified surface structure and composition for their fabrication.

  18. Green synthesis of anisotropic gold nanoparticles for photothermal therapy of cancer.

    Science.gov (United States)

    Fazal, Sajid; Jayasree, Aswathy; Sasidharan, Sisini; Koyakutty, Manzoor; Nair, Shantikumar V; Menon, Deepthy

    2014-06-11

    Nanoparticles of varying composition, size, shape, and architecture have been explored for use as photothermal agents in the field of cancer nanomedicine. Among them, gold nanoparticles provide a simple platform for thermal ablation owing to its biocompatibility in vivo. However, the synthesis of such gold nanoparticles exhibiting suitable properties for photothermal activity involves cumbersome routes using toxic chemicals as capping agents, which can cause concerns in vivo. Herein, gold nanoparticles, synthesized using green chemistry routes possessing near-infrared (NIR) absorbance facilitating photothermal therapy, would be a viable alternative. In this study, anisotropic gold nanoparticles were synthesized using an aqueous route with cocoa extract which served both as a reducing and stabilizing agent. The as-prepared gold nanoparticles were subjected to density gradient centrifugation to maximize its NIR absorption in the wavelength range of 800-1000 nm. The particles also showed good biocompatibility when tested in vitro using A431, MDA-MB231, L929, and NIH-3T3 cell lines up to concentrations of 200 μg/mL. Cell death induced in epidermoid carcinoma A431 cells upon irradiation with a femtosecond laser at 800 nm at a low power density of 6 W/cm(2) proved the suitability of green synthesized NIR absorbing anisotropic gold nanoparticles for photothermal ablation of cancer cells. These gold nanoparticles also showed good X-ray contrast when tested using computed tomography (CT), proving their feasibility for use as a contrast agent as well. This is the first report on green synthesized anisotropic and cytocompatible gold nanoparticles without any capping agents and their suitability for photothermal therapy.

  19. Effect of gold nanoparticle on stability of the DNA molecule: A study of molecular dynamics simulation.

    Science.gov (United States)

    Izanloo, Cobra

    2017-09-26

    An understanding of the mechanism of DNA interactions with gold nanoparticles is useful in today medicine applications. We have performed a molecular dynamics simulation on a B-DNA duplex (CCTCAGGCCTCC) in the vicinity of a gold nanoparticle with a truncated octahedron structure composed of 201 gold atoms (diameter ∼1.8 nm) to investigate gold nanoparticle (GNP) effects on the stability of DNA. During simulation, the nanoparticle is closed to DNA and phosphate groups direct the particles into the major grooves of the DNA molecule. Because of peeling and untwisting states that are occur at end of DNA, the nucleotide base lies flat on the surface of GNP. The configuration entropy is estimated using the covariance matrix of atom-positional fluctuations for different bases. The results show that when a gold nanoparticle has interaction with DNA, entropy increases. The results of conformational energy and the hydrogen bond numbers for DNA indicated that DNA becomes unstable in the vicinity of a gold nanoparticle. The radial distribution function was calculated for water hydrogen-phosphate oxygen pairs. Almost for all nucleotide, the presence of a nanoparticle around DNA caused water molecules to be released from the DNA duplex and cations were close to the DNA.

  20. Characterization and antimicrobial application of biosynthesized gold and silver nanoparticles by using Microbacterium resistens.

    Science.gov (United States)

    Wang, Chao; Singh, Priyanka; Kim, Yeon Ju; Mathiyalagan, Ramya; Myagmarjav, Davaajargal; Wang, Dandan; Jin, Chi-Gyu; Yang, Deok Chun

    2016-11-01

    Various microorganisms were found to be cable of synthesizing gold and silver nanoparticles when gold and silver salts were supplied in the reaction system. The main objective of this study was to evaluate the extracellular synthesis of gold and silver nanoparticles by the type strain Microbacterium resistens(T) [KACC14505]. The biosynthesized gold and silver nanoparticles were characterized by ultraviolet-visible spectroscopy (UV-Vis), field emission transmission electron micrograph (FE-TEM), energy dispersive X-ray spectroscopy (EDX), elemental mapping, and dynamic light scattering (DLS). Moreover, the nanoparticles were evaluated for antimicrobial potential against various pathogenic microorganisms such as Vibrio parahaemolyticus [ATCC 33844], Salmonella enterica [ATCC 13076], Staphylococcus aureus [ATCC 6538], Bacillus anthracis [NCTC 10340], Bacillus cereus [ATCC 14579], Escherichia coli [ATCC 10798], and Candida albicans [KACC 30062]. The silver nanoparticles were found as a potent antimicrobial agent whereas gold nanoparticles not showed any ability. Therefore, the current study describes the simple, green, and extracellular synthesis of gold and silver nanoparticles by the type strain Microbacterium resistens(T) [KACC14505].

  1. Shape-controlled synthesis of NIR absorbing branched gold nanoparticles and morphology stabilization with alkanethiols

    Science.gov (United States)

    Van de Broek, B.; Frederix, F.; Bonroy, K.; Jans, H.; Jans, K.; Borghs, G.; Maes, G.

    2011-01-01

    Gold nanoparticles are ideal candidates for clinical applications if their plasmon absorption band is situated in the near infrared region (NIR) of the electromagnetic spectrum. Various parameters, including the nanoparticle shape, strongly influence the position of this absorption band. The aim of this study is to produce stabilized NIR absorbing branched gold nanoparticles with potential for biomedical applications. Hereto, the synthesis procedure for branched gold nanoparticles is optimized varying the different synthesis parameters. By subsequent electroless gold plating the plasmon absorption band is shifted to 747.2 nm. The intrinsic unstable nature of the nanoparticles' morphology can be clearly observed by a spectral shift and limits their use in real applications. However, in this article we show how the stabilization of the branched structure can be successfully achieved by exchanging the initial capping agent for different alkanethiols and disulfides. Furthermore, when using alkanethiols/disulfides with poly(ethylene oxide) units incorporated, an increased stability of the gold nanoparticles is achieved in high salt concentrations up to 1 M and in a cell culture medium. These achievements open a plethora of opportunities for these stabilized branched gold nanoparticles in nanomedicine.

  2. Shape-controlled synthesis of NIR absorbing branched gold nanoparticles and morphology stabilization with alkanethiols

    Energy Technology Data Exchange (ETDEWEB)

    Van de Broek, B; Frederix, F; Bonroy, K; Jans, H; Jans, K; Borghs, G [imec, SSET-Functional Nanosystems, Kapeldreef 75, 3001 Leuven (Belgium); Maes, G, E-mail: Bieke.Vandebroek@imec.be [Katholieke Universiteit Leuven, Physical and Quantum Chemistry, Celestijnenlaan 200F, 3001 Leuven (Belgium)

    2011-01-07

    Gold nanoparticles are ideal candidates for clinical applications if their plasmon absorption band is situated in the near infrared region (NIR) of the electromagnetic spectrum. Various parameters, including the nanoparticle shape, strongly influence the position of this absorption band. The aim of this study is to produce stabilized NIR absorbing branched gold nanoparticles with potential for biomedical applications. Hereto, the synthesis procedure for branched gold nanoparticles is optimized varying the different synthesis parameters. By subsequent electroless gold plating the plasmon absorption band is shifted to 747.2 nm. The intrinsic unstable nature of the nanoparticles' morphology can be clearly observed by a spectral shift and limits their use in real applications. However, in this article we show how the stabilization of the branched structure can be successfully achieved by exchanging the initial capping agent for different alkanethiols and disulfides. Furthermore, when using alkanethiols/disulfides with poly(ethylene oxide) units incorporated, an increased stability of the gold nanoparticles is achieved in high salt concentrations up to 1 M and in a cell culture medium. These achievements open a plethora of opportunities for these stabilized branched gold nanoparticles in nanomedicine.

  3. Shape-controlled synthesis of NIR absorbing branched gold nanoparticles and morphology stabilization with alkanethiols.

    Science.gov (United States)

    Van de Broek, B; Frederix, F; Bonroy, K; Jans, H; Jans, K; Borghs, G; Maes, G

    2011-01-07

    Gold nanoparticles are ideal candidates for clinical applications if their plasmon absorption band is situated in the near infrared region (NIR) of the electromagnetic spectrum. Various parameters, including the nanoparticle shape, strongly influence the position of this absorption band. The aim of this study is to produce stabilized NIR absorbing branched gold nanoparticles with potential for biomedical applications. Hereto, the synthesis procedure for branched gold nanoparticles is optimized varying the different synthesis parameters. By subsequent electroless gold plating the plasmon absorption band is shifted to 747.2 nm. The intrinsic unstable nature of the nanoparticles' morphology can be clearly observed by a spectral shift and limits their use in real applications. However, in this article we show how the stabilization of the branched structure can be successfully achieved by exchanging the initial capping agent for different alkanethiols and disulfides. Furthermore, when using alkanethiols/disulfides with poly(ethylene oxide) units incorporated, an increased stability of the gold nanoparticles is achieved in high salt concentrations up to 1 M and in a cell culture medium. These achievements open a plethora of opportunities for these stabilized branched gold nanoparticles in nanomedicine.

  4. Biosynthesis, structural characterization and antimicrobial activity of gold and silver nanoparticles.

    Science.gov (United States)

    Ahmad, Tokeer; Wani, Irshad A; Manzoor, Nikhat; Ahmed, Jahangeer; Asiri, Abdullah M

    2013-07-01

    An eco friendly simple biosynthetic route was used for the preparation of monodisperse and highly crystalline gold and silver nanoparticles using cell free extract of fungus, Candida albicans. Transmission electron microscopic studies show the formation of gold and silver nanocrystals of average size of 5 nm and 30 nm with the specific surface areas of 18.9 m(2)/g and 184.4 m(2)/g respectively. The interaction of gold and silver nanoparticles with proteins has been formulated by FT-IR spectroscopy and thermal gravimetric analysis. The formation of gold and silver nanoparticles was also confirmed by the appearance of a surface plasmon band at 540 nm and 450 nm respectively. The antimicrobial activity of the synthesized gold and silver nanoparticles was investigated against both Staphylococcus aureus and Escherichia coli. The results suggest that these nanoparticles can be used as effective growth inhibitors against the test microorganisms. Greater bactericidal activity was observed for silver nanoparticles. The E. coli, a gram negative bacterium was found to be more susceptible to gold and silver nanoparticles than the S. aureus, a gram positive bacterium.

  5. GoldMag nanoparticles with core/shell structure: characterization and application in MR molecular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Song; Zou Liguang, E-mail: kxyjzy@yahoo.cn; Zhang Dong; Pang Xin; Yang Hua [Xinqiao Hospital, Third Military Medical University, Department of Radiology (China); Xu Ying [Xinqiao Hospital, Third Military Medical University, Base for Drug Clinical Trial (China)

    2011-09-15

    GoldMag is a kind of bi-functional nanoparticle, composed of a gold nanoshell and an iron oxide core. GoldMag combines the antibody immobilization property of gold nanoshell with the superparamagnetic feature of the iron oxide core. Rabbit anti-mouse IgG was immobilized on the surface of GoldMag to synthesize GoldMag-IgG in a single-step process. Transmission electron microscopy, UV/Vis spectrophotometry, zeta potential analysis, dynamic light scattering, enzyme-linked immunosorbent assay, and magnetic resonance imaging (MRI) were employed to characterize the nanostructures and the spectroscopic and magnetic properties of GoldMag and GoldMag-IgG. The antibody encapsulation efficiency of GoldMag was measured as 58.7%, and the antibody loading capacity was 88 {mu}g IgG per milligram of GoldMag. The immunoactivity of GoldMag-IgG was estimated to be 43.3% of that of the original IgG. The cytotoxicity of GoldMag was assessed by MTT assay, which showed that it has only little influence on human dermal lymphatic endothelial cells. MR imaging of different concentrations of ultrasmall superparamagnetic iron oxide, GoldMag, and GoldMag-IgG showed that 3 {mu}g/mL of nanoparticles could significantly affect the MRI signal intensity of GRE T2*WI. The results demonstrate that GoldMag nanoparticles can be effectively conjugated with biomacromolecules and possess great potential for MR molecular imaging.

  6. GoldMag nanoparticles with core/shell structure: characterization and application in MR molecular imaging

    Science.gov (United States)

    Zhang, Song; Zou, Liguang; Zhang, Dong; Pang, Xin; Yang, Hua; Xu, Ying

    2011-09-01

    GoldMag is a kind of bi-functional nanoparticle, composed of a gold nanoshell and an iron oxide core. GoldMag combines the antibody immobilization property of gold nanoshell with the superparamagnetic feature of the iron oxide core. Rabbit anti-mouse IgG was immobilized on the surface of GoldMag to synthesize GoldMag-IgG in a single-step process. Transmission electron microscopy, UV/Vis spectrophotometry, zeta potential analysis, dynamic light scattering, enzyme-linked immunosorbent assay, and magnetic resonance imaging (MRI) were employed to characterize the nanostructures and the spectroscopic and magnetic properties of GoldMag and GoldMag-IgG. The antibody encapsulation efficiency of GoldMag was measured as 58.7%, and the antibody loading capacity was 88 μg IgG per milligram of GoldMag. The immunoactivity of GoldMag-IgG was estimated to be 43.3% of that of the original IgG. The cytotoxicity of GoldMag was assessed by MTT assay, which showed that it has only little influence on human dermal lymphatic endothelial cells. MR imaging of different concentrations of ultrasmall superparamagnetic iron oxide, GoldMag, and GoldMag-IgG showed that 3 μg/mL of nanoparticles could significantly affect the MRI signal intensity of GRE T2*WI. The results demonstrate that GoldMag nanoparticles can be effectively conjugated with biomacromolecules and possess great potential for MR molecular imaging.

  7. Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode

    Directory of Open Access Journals (Sweden)

    Ayşem Üzer

    2016-08-01

    Full Text Available Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au was functionalized with p-aminothiophenol (p-ATP and modified with gold nanoparticles (Au-NPs to manufacture the final (Au/p-ATP-Aunano electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl4 solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano using square wave voltammetry (SWV in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5–50 mg·L−1 nitrite with a limit of detection (LOD of 0.12 mg·L−1. Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO2− solution and in sausage sample solution, to which different concentrations of NO2− standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples.

  8. Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode.

    Science.gov (United States)

    Üzer, Ayşem; Sağlam, Şener; Can, Ziya; Erçağ, Erol; Apak, Reşat

    2016-08-02

    Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au) was functionalized with p-aminothiophenol (p-ATP) and modified with gold nanoparticles (Au-NPs) to manufacture the final (Au/p-ATP-Aunano) electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP) coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl₄ solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano) using square wave voltammetry (SWV) in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5-50 mg·L(-1) nitrite with a limit of detection (LOD) of 0.12 mg·L(-1). Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs) and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO₂(-) solution and in sausage sample solution, to which different concentrations of NO₂(-) standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples.

  9. Electrochemical Determination of Food Preservative Nitrite with Gold Nanoparticles/p-Aminothiophenol-Modified Gold Electrode

    Science.gov (United States)

    Üzer, Ayşem; Sağlam, Şener; Can, Ziya; Erçağ, Erol; Apak, Reşat

    2016-01-01

    Due to the negative impact of nitrate and nitrite on human health, their presence exceeding acceptable levels is not desired in foodstuffs. Thus, nitrite determination at low concentrations is a major challenge in electroanalytical chemistry, which can be achieved by fast, cheap, and safe electrochemical sensors. In this work, the working electrode (Au) was functionalized with p-aminothiophenol (p-ATP) and modified with gold nanoparticles (Au-NPs) to manufacture the final (Au/p-ATP-Aunano) electrode in a two-step procedure. In the first step, p-ATP was electropolymerized on the electrode surface to obtain a polyaminothiophenol (PATP) coating. In the second step, Au/p-ATP-Aunano working electrode was prepared by coating the surface with the use of HAuCl4 solution and cyclic voltammetry. Determination of aqueous nitrite samples was performed with the proposed electrode (Au/p-ATP-Aunano) using square wave voltammetry (SWV) in pH 4 buffer medium. Characteristic peak potential of nitrite samples was 0.76 V, and linear calibration curves of current intensity versus concentration was linear in the range of 0.5–50 mg·L−1 nitrite with a limit of detection (LOD) of 0.12 mg·L−1. Alternatively, nitrite in sausage samples could be colorimetrically determined with high sensitivity by means of p-ATP‒modified gold nanoparticles (AuNPs) and naphthylethylene diamine as coupling agents for azo-dye formation due to enhanced charge-transfer interactions with the AuNPs surface. The slopes of the calibration lines in pure NO2− solution and in sausage sample solution, to which different concentrations of NO2− standards were added, were not significantly different from each other, confirming the robustness and interference tolerance of the method. The proposed voltammetric sensing method was validated against the colorimetric nanosensing method in sausage samples. PMID:27490543

  10. Targeted images of KB cells using folate-conjugated gold nanoparticles

    Science.gov (United States)

    Rathinaraj, Pierson; Lee, Kyubae; Park, Soo-Young; Kang, Inn-Kyu

    2015-01-01

    Mercaptosuccinic acid-coated gold (GM) nanoparticles were prepared and characterized by transmission electron microscopy and dynamic light scattering. Folic acid (F) was then conjugated to the GM to preferentially target oral squamous cancer (KB) cells with folate receptors expressed on their membranes and facilitate the transit of the nanoparticles across the cell membrane. Finally, a fluorescence dye (Atto) was conjugated to the nanoparticles to visualize their internalization into KB cells. After culture of the cells in a medium containing GM and folate-conjugated GM (GF), the interaction of surface-modified gold nanoparticles with KB cells was studied.

  11. Biosynthesis and Characterization of Gold and Silver Nanoparticles Using Milk Thistle (Silybum marianum Seed Extract

    Directory of Open Access Journals (Sweden)

    R. Gopalakrishnan

    2014-01-01

    Full Text Available Biogenic synthesis of gold and silver nanoparticles from aqueous solutions using milk thistle (Silybum marianum seed extract as reducing and stabilizing agent has been reported. Formation and stabilization of nanoparticles were monitored using surface plasmon resonance (SPR bands of UV-Vis spectroscopy. Morphology of gold and silver nanoparticles was investigated using X-ray diffraction, high-resolution transmission electron microscopy with selected area electron diffraction analysis, and dynamic light scattering. Fourier transform-infrared spectroscopy was employed to identify the possible biomolecules responsible for the reduction and stabilization of nanoparticles.

  12. Photofragmentation of colloidal solutions of gold nanoparticles under femtosecond laser pulses in IR and visible ranges

    Energy Technology Data Exchange (ETDEWEB)

    Danilov, P A; Zayarnyi, D A; Ionin, A A; Kudryashov, S I; Makarov, S V; Rudenko, A A; Saraeva, I N; Yurovskikh, V I [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Lednev, V N; Pershin, S M [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-05-31

    The specific features of photofragmentation of sols of gold nanoparticles under focused femtosecond laser pulses in IR (1030 nm) and visible (515 nm) ranges is experimentally investigated. A high photofragmentation efficiency of nanoparticles in the waist of a pulsed laser beam in the visible range (at moderate radiation scattering) is demonstrated; this efficiency is related to the excitation of plasmon resonance in nanoparticles on the blue shoulder of its spectrum, in contrast to the regime of very weak photofragmentation in an IR-laser field of comparable intensity. Possible mechanisms of femtosecond laser photofragmentation of gold nanoparticles are discussed. (extreme light fields and their applications)

  13. Gold nanoparticles: Optical properties and implementations in cancer diagnosis and photothermal therapy

    Directory of Open Access Journals (Sweden)

    Xiaohua Huang

    2010-01-01

    Full Text Available Currently a popular area in nanomedicine is the implementation of plasmonic gold nanoparticles for cancer diagnosis and photothermal therapy, attributed to the intriguing optical properties of the nanoparticles. The surface plasmon resonance, a unique phenomenon to plasmonic (noble metal nanoparticles leads to strong electromagnetic fields on the particle surface and consequently enhances all the radiative properties such as absorption and scattering. Additionally, the strongly absorbed light is converted to heat quickly via a series of nonradiative processes. In this review, we discuss these important optical and photothermal properties of gold nanoparticles in different shapes and structures and address their recent applications for cancer imaging, spectroscopic detection and photothermal therapy.

  14. The filtration of colloidal gold nanoparticles with carbon nanotubes

    Science.gov (United States)

    de Jong, Frans Jan; Buffet, Adeline

    2016-11-01

    Understanding the local filtering of nanoparticles (NPs) is essential for the development and optimization of medical and industrial applications. Microfocus small-angle X-ray scattering (μSAXS) was used to determine the local filtration kinetics of 100 nm sized colloidal gold nanoparticles (Au NPs) within a multi-walled carbon nanotube (MWCNT) forest. To get a physical insight into the Au NP filtration process within the MWCNT forest a novel model based on the well-known DLVO theory was developed. The DLVO theory is commonly used to describe the interaction between colloidal particles. In addition to the attractive Van de Waals force and the electrostatic double-layer force, a non-DLVO force is added to account for hydration and hydrophobic effects. The model presented here shows that the Au NPs are mainly unfavorably deposited into the so-called secondary energy minimum. This latter finding is in good agreement with the experimental observations and the literature, in which unfavorable particle deposition is related to deposition into the secondary energy minimum. The use of μSAXS to get a physical insight into the local deposition kinetics of submicrometer particles opens up new pathways to optimize the preparation of MWCNT forests for filtration purposes.

  15. Gold coated lanthanide phosphate nanoparticles for targeted alpha generator radiotherapy.

    Directory of Open Access Journals (Sweden)

    Mark F McLaughlin

    Full Text Available Targeted radiotherapies maximize cytotoxicty to cancer cells. In vivo α-generator targeted radiotherapies can deliver multiple α particles to a receptor site dramatically amplifying the radiation dose delivered to the target. The major challenge with α-generator radiotherapies is that traditional chelating moieties are unable to sequester the radioactive daughters in the bioconjugate which is critical to minimize toxicity to healthy, non-target tissue. The recoil energy of the (225Ac daughters following α decay will sever any metal-ligand bond used to form the bioconjugate. This work demonstrates that an engineered multilayered nanoparticle-antibody conjugate can deliver multiple α radiations and contain the decay daughters of (225Ac while targeting biologically relevant receptors in a female BALB/c mouse model. These multi-shell nanoparticles combine the radiation resistance of lanthanide phosphate to contain (225Ac and its radioactive decay daughters, the magnetic properties of gadolinium phosphate for easy separation, and established gold chemistry for attachment of targeting moieties.

  16. Visible luminescence in polyaniline/(gold nanoparticle) composites

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Renata F. S. [Universidade Federal de Pernambuco, Pos-Graduacao em Ciencia de Materiais (Brazil); Andrade, Cesar A. S. [Universidade Federal de Pernambuco, Departamento de Bioquimica (Brazil); Santos, Clecio G. dos [Instituto de Educacao, Ciencia e Tecnologia de Pernambuco (Brazil); Melo, Celso P. de, E-mail: celso@df.ufpe.br [Universidade Federal de Pernambuco, Pos-Graduacao em Ciencia de Materiais (Brazil)

    2013-01-15

    We describe the use of solution chemistry methods to prepare polyaniline/(gold nanoparticles)-PANI/AuNPs-composites as colloidal particles that exhibit an intense green fluorescence after excitation in the ultraviolet region. Measurements of the relative fluorescence quantum yield indicate that the intensity of the observed luminescence of these nanocomposites is a few orders of magnitude higher than the corresponding fluorescence of either the isolated polymer or the pure AuNPs. Hence, cooperative effects between the conducting polymer chains and the metallic particles must dominate the emission behavior of these materials. Transmission electron microscopy reveals the existence of metal nanoparticle aggregates with sizes in the 2-3 nm range dispersed in the polymer matrix. By implementing an experimental planning, we have been able to change the preparation parameters so as to vary in a controlled manner the intensity and the profile of the luminescence spectrum as well as the size and aggregation characteristics of the colloidal particles. We also show that when the pH of the medium is varied, the dielectric properties (such as the degree of conductivity) of the PANI/AuNPs colloidal solutions and the intensity of their luminescence change in a consistent manner. Due to the polycation nature of the doped PANI chains, we suggest that these composites may find interesting applications as fluorescent markers of biologic molecules.

  17. Behavior of colloidal gold nanoparticles in different ionic strength media

    Energy Technology Data Exchange (ETDEWEB)

    Barreto, Ângela; Luis, Luis G. [University of Aveiro, Depa