Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Current research into semiconductor clusters is focused on the properties of quantum dots-fragments of semiconductor consisting of hundreds to many thousands of atoms-with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size-dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.

Semiconductor Clusters, Nanocrystals, and Quantum Dots

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Semiconductor nanocrystals were prepared for use as fluorescent probes in biological staining and diagnostics. Compared with conventional fluorophores, the nanocrystals have a narrow, tunable, symmetric emission spectrum and are photochemically stable. The advantages of the broad, continuous excitation spectrum were demonstrated in a dual-emission, single-excitation labeling experiment on mouse fibroblasts. These nanocrystal probes are thus complementary and in some cases may be superior to existing fluorophores.

https://science.sciencemag.org/content/sci/281/5385/2013.full.pdf

Semiconductor Nanocrystals as Fluorescent Biological Labels

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Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

Nanoparticles of CdTe were found to spontaneously reorganize into crystalline nanowires upon controlled removal of the protective shell of organic stabilizer. The intermediate step in the nanowire formation was found to be pearl-necklace aggregates. Strong dipole-dipole interaction is believed to be the driving force of nanoparticle self-organization. The linear aggregates subsequently recrystallized into nanowires whose diameter was determined by the diameter of the nanoparticles. The produced nanowires have high aspect ratio, uniformity, and optical activity. These findings demonstrate the collective behavior of nanoparticles as well as a convenient, simple technique for production of one-dimensional semiconductor colloids suitable for subsequent processing into quantum-confined superstructures, materials, and devices.

https://science.sciencemag.org/content/sci/297/5579/237.full.pdf

Spontaneous organization of single CdTe nanoparticles into luminescent nanowires.

Improved synthetic routes and size-selective precipitation have enabled the preparation of almost monodisperse CdS clusters. Six samples of 1-thioglycerol stabilized clusters with diameters of approximately 13,14,16,19, 23, and 39 A have been prepared as fully redispersible powders and were characterized by elemental analysis, powder X-ray diffraction, electron microscopy, thermogravimetric analysis, and UV-vis spectroscopy. Smallangle X-ray scattering was used to determine the mean cluster size. The well-structured UV-vis spectra reveal that the size-dependent shift of the Is-Is excitonic transition is in agreement with the tight-binding theory and the pseudopotential theory. Moreover, as expected by quantum mechanical calculations the oscillator strength of the transition increases proportional to 1 /r3. UV-vis spectra taken at various temperatures between 4 and 295 K have shown that the temperature shift of the excitonic transition energy becomes stronger with decreasing particle size. Strong, reversible absorbance shifts were observed, upon transferring the clusters from their solutions onto quartz plates and vice versa.

CdS Nanoclusters: Synthesis, Characterization, Size Dependent Oscillator Strength, Temperature Shift of the Excitonic Transition Energy, and Reversible Absorbance Shift

Colloidal silver sols of long-time stability are formed in the γ-irradiation of 1.0 × 10-4 M AgClO4 solutions, which also contain 0.3 M 2-propanol, 2.5 × 10-2 M N2O, and sodium citrate in various concentrations. The reduction of Ag+ in these solutions is brought about by the 1-hydroxyalkyl radical generated in the radiolysis of 2-propanol; citrate does not act as a reductant but solely as a stabilizer of the colloidal particles formed. Its concentration is varied in the range from 5.0 × 10-5 to 1.5 × 10-3 M, and the size and size distribution of the silver particles are studied by electron microscopy. At low citrate concentration, partly agglomerated large particles are formed that have many imperfections. In an intermediate range (a few 10-4 M), well-separated particles with a rather narrow size distribution and little imperfections are formed, the size slightly decreasing with increasing citrate concentration. At high citrate concentrations, large lumps of coalesced silver particles are present, due to ...

Formation of Colloidal Silver Nanoparticles: Capping Action of Citrate

published in Advance ACS Abstracts, November 1, 1993. (1) (a) Pieranski, P.; Strzelecki, L.; Pansu, B. Phys. Rev. Lett. 1983, 50,900. (b) Pansu, B.; Pieranski, P. J. Phys. (Paris) 1984,45,331. (c) Pieranski, P. Phys. Rev. Lett. 1980,45,569. (2) Van Winkle, D. H.; Murray, C. A. Phys. Rev. A 1986, 34, 562. (3) Onoda, G. Y. Phys. Rev. Lett. 1985,55, 226. (4) Giersig, M.; Kunath, W. Eur. J. Biol. Suppl. 1989, 27, 28. (5) Denkov, N. D.; Velev, 0. D.; Kralchevsky, P. A.; Ivanov, I. B.; Yoshimura, H.; Nagayama, K. Langmuir 1992,8, 3183. (6) Dusemund, B.; Hoffmann, A,; Salzmann, T.; Kreibig, U.; Schmid, G. 2. Phys. D 1991,20, 305. (7) Brom, H. B.;van Staveren, M. P. J.; de Jongh, L. J.Z. Phys. D 1991, 20, 281. (Munich) 1990,169, 11. (8) Kreibig,U.;Fauth, K.; Granqvist, C.-G.; Schmid, G. Z.Phys. Chem. (9) Deriarmin. B. V.: Muller. V. M.: Rabinovich. Ya. I. Kolloid Zh. 1969, 31, 302. . (10) Parsegian,V. A.; Weiss, G. H.; Schrader,M. E. J. Colloidlnterjace Sci. 1977, 61, 356. (11) Parsegian, V.

Preparation of ordered colloid monolayers by electrophoretic deposition

The fabrication of magnetic composite core−shell particles and hollow spheres with tailored dimensions and compositions has been accomplished by a multistep (layer-by-layer) strategy. Composite particles were prepared by coating submicrometer-sized anionic polystyrene (PS) latices with magnetite (Fe3O4) nanoparticle layers alternately adsorbed with polyelectrolyte from aqueous solution. The thickness of the deposited multilayers could be finely tuned with nanoscale precision, either by selection of the number of adsorption cycles performed or by the number of polyelectrolyte layers deposited between each nanoparticle layer (i.e., interlayer). As demonstrated by transmission electron microscopy, a marked improvement in the growth, uniformity, and regularity of the composite multilayers was achieved when the number of polyelectrolyte interlayers was increased from one [(poly(diallyldimethylammonium chloride) (PDADMAC)] to three [(PDADMAC/poly(styrenesulfonate) (PSS)/PDADMAC)]. Hollow, intact magnetic sphere...

Michael Giersig

Papers

Spontaneous organization of single CdTe nanoparticles into luminescent nanowires.

CdS Nanoclusters: Synthesis, Characterization, Size Dependent Oscillator Strength, Temperature Shift of the Excitonic Transition Energy, and Reversible Absorbance Shift

Formation of Colloidal Silver Nanoparticles: Capping Action of Citrate

Preparation of ordered colloid monolayers by electrophoretic deposition

Magnetic Nanocomposite Particles and Hollow Spheres Constructed by a Sequential Layering Approach