Gold nanorods with aspect ratios of 4.6 ± 1.2, 13 2, and 18 2.5 (all 16 3 nm short axis) are prepared by a seeding growth approach in the presence an aqueous miceller template. Citrate-capped 3.5 diameter gold particles, reduction HAuCl4 borohydride, used as seed. The ratio is controlled varying seed to metal salt. long rods isolated from spherical particles centrifugation.

A series of gold nanoparticles were examined for uptake and acute toxicity in human leukemia cells. The (average diameter=18 nm), which possessed various surface modifiers, not toxic to cells during continuous exposure three days. Citrate-capped further their cellular by absorbance transmission electron microscopy (see image). Results indicate that although some precursors may be toxic, the themselves are necessarily detrimental function. results Nanoscience nanotechnology hold great promise...

Gold, enigmatically represented by the target-like design of its ancient alchemical symbol, has been considered a mystical material great value for centuries. Nanoscale particles gold now command deal attention biomedical applications. Depending on their size, shape, degree aggregation, and local environment, nanoparticles can appear red, blue, or other colors. These visible colors reflect underlying coherent oscillations conduction-band electrons ("plasmons") upon irradiation with light...

A seed-mediated growth approach to improved monodispersity of nanoparticles that involves controlling nucleation and in solution is presented. Using this approach, spheroidal rod-like gold particles (see Figure) could be prepared the presence a micellar template. The aspect ratio varied from 1 10 by varying preformed seed metal salt.

A seed-mediated growth method was used to control the morphology and dimensions of Au nanocrystals by manipulation experimental parameters in aqueous solution at room temperature. This chemical route produces various structural architectures with rod-, rectangle-, hexagon-, cube-, triangle-, starlike profiles branched (such as bi-, tri-, tetra-, multipod) high yield presence a single surfactant, cetyltrimethylammonium bromide.

Gold nanoparticles have attracted enormous scientific and technological interest due to their ease of synthesis, chemical stability, unique optical properties. Proof-of-concept studies demonstrate biomedical applications in sensing, biological imaging, drug delivery, cancer treatment. Knowledge about potential toxicity health impact is essential before these nanomaterials can be used real clinical settings. Furthermore, the underlying interactions with physiological fluids a key feature...

Short gold nanorods of average lengths ranging between 20 and 100 nm (with corresponding aspect ratios 2 4) were synthesized in excellent yield (approximately 97%). These characterized by dark-field microscopy, UV-visible spectrophotometry, transmission electron microscopy. Temporal evolution rod shape had also been followed spectrophotometry microscopy indicates that the briefly increase length, then slightly width, as they grow. The effect synthetic parameters on dimension was explored to...

Following a seeding growth approach, gold nanoparticles of diameters 5−40 nm were prepared with 10−15% standard deviation in diameter from 3.5 ± 0.7 particle seeds. Particle size can be controlled by varying the ratio seed to metal salt, and thus any range prepared. The method also scaled up produce 10−100 mg nanoparticles.

Using a seed-mediated growth approach in rodlike micellar media, silver nanorods of varied aspect ratio were prepared from nearly spherical 4 nm nanoparticles.

Semiconductors and metals exhibit unusual optical, electronic, magnetic properties on the nanometer scale. Chemists materials scientists are developing methods to make non-spherical shapes of semiconductors We use a seed-mediated growth approach metallic nanorods nanowires in homogeneous solution. Control ratio spherical seeds metal salt reduction reaction contyrols aspect resulting rods wires.

Gold nanorods of different aspect ratios are prepared using the growth-directing surfactant, cetyltrimethylammonium bromide (CTAB), which forms a bilayer on gold nanorod surface. Toxicological assays CTAB-capped solutions with human colon carcinoma cells (HT-29) reveal that apparent cytotoxicity is caused by free CTAB in solution. Overcoating polymers substantially reduces cytotoxicity. The number taken up per cell, for surface coatings, quantitated inductively coupled plasma mass...

Gold nanorods were prepared via a seed-mediated sequential growth process involving the use of citrate-stabilised seed crystals and their subsequent in series reaction solutions containing [AuCl4]−, ascorbic acid cationic surfactant cetyltrimethylammonuim bromide (CTAB). Electron diffraction analysis HRTEM images mature showed superpositions two specific pairs crystallographic zones, either <112> <100> or <110> <111>, which consistent with cyclic penta-twinned crystal five {111} twin...

Rapid photoinduced electron transfer is demonstrated over a distance of greater than 40 angstroms between metallointercalators that are tethered to the 5′ termini 15-base pair DNA duplex. An oligomeric assembly was synthesized in which donor Ru(phen) 2 dppz 2+ (phen, phenanthroline, and dppz, dipyridophenazine) acceptor Rh(phi) phen 3+ (phi, phenanthrenequinone diimine). These metal complexes intercalated either one or two base steps from helix termini. Although ruthenium-modified...

We report studies on the synthesis of gold nanorods by a three-step seeding protocol method using variety different seeds. The synthetic is adapted from one we published earlier (Jana et al. J. Phys. Chem. B 2001, 105, 4065). seeds chosen for these have average diameters in range 4 to 18 nm, with positively charged as well negatively surface groups. In all cases, along large concentration long rods, small number shapes such triangles, hexagons, and rods are observed. proportion increases an...

In recent years, there has been a great deal of interest in the preparation and application nanoparticles for cancer therapy. Gold are especially suited to thermal destruction due their ease surface functionalization photothermal heating ability. Here, we review progress gold nanoparticle-mediated therapies. We begin with an introduction properties heat-generating mechanisms which have established. The pioneering work therapy is discussed along effects on cells vitro. Additionally,...

By using seed‐mediation and careful control of pH , gold nanorods high aspect ratio (∼ 18–25, 20 in the Figure) have been produced by surfactant‐directed synthesis. The yield is 90 %) method can be readily adapted for scaling up.

Central to the concept of seed-mediated growth nanoparticles is that small nanoparticle seeds serve as nucleation centers grow a desired size. We have examined this common assumption in model system, wet chemical synthesis gold via reduction salt, by transmission electron microscopy and electronic absorption spectroscopy. find changing seed concentration does affect size product nanoparticles, but method reagent addition drastically affects outcome even more. For fast reducing agent,...

The seed-mediated approach to making gold nanorods in aqueous surfactant solutions has become tremendously popular recent years. Unlike the use of strong chemical reductants make spherical nanoparticles, growth requires weak reducing conditions, leading an unknown degree reduction. metal content nanorods, made high yield presence silver ion, is determined by inductively coupled plasma atomic emission spectroscopy. Through known concentration molar extinction coefficients are calculated for...

A major challenge in nanoscience and nanotechnology is the rational assembly of nanoscale objects. Here we report that gold nanorods, aspect ratio 18, can be functionalized with a biotin disulfide, subsequent addition streptavidin links rods together an end-to-end manner much more often than expected.

The synthesis and photophysical characterization of nanometer-size ZnS with without Mn2+ are reported. Without Mn2+, the nanoclusters emit in blue upon ultraviolet excitation. doped 1−5% (presumably Zn2+ sites) yields orange emission observed for bulk Zn:Mn phosphors but greatly reduced emissive lifetimes. surface-bound contrast, emits even shorter Thus, physical location nanocluster determines its optical properties.