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.

We have used the pH-induced self-assembly of a peptide-amphiphile to make a nanostructured fibrous scaffold reminiscent of extracellular matrix. The design of this peptide-amphiphile allows the nanofibers to be reversibly cross-linked to enhance or decrease their structural integrity. After cross-linking, the fibers are able to direct mineralization of hydroxyapatite to form a composite material in which the crystallographic c axes of hydroxyapatite are aligned with the long axes of the fibers. This alignment is the same as that observed between collagen fibrils and hydroxyapatite crystals in bone.

http://science.sciencemag.org/content/sci/294/5547/1684.full.pdf

Self-assembly and mineralization of peptide-amphiphile nanofibers

In recent work with large high-symmetry viruses, single-particle electron cryomicroscopy (cryo-EM) has achieved the determination of near-atomic-resolution structures by allowing direct fitting of atomic models into experimental density maps. However, achieving this goal with smaller particles of lower symmetry remains challenging. Using a newly developed single electron-counting detector, we confirmed that electron beam-induced motion substantially degrades resolution, and we showed that the combination of rapid readout and nearly noiseless electron counting allow image blurring to be corrected to subpixel accuracy, restoring intrinsic image information to high resolution (Thon rings visible to ∼3 A). Using this approach, we determined a 3.3-A-resolution structure of an ∼700-kDa protein with D7 symmetry, the Thermoplasma acidophilum 20S proteasome, showing clear side-chain density. Our method greatly enhances image quality and data acquisition efficiency-key bottlenecks in applying near-atomic-resolution cryo-EM to a broad range of protein samples.

Electron counting and beam-induced motion correction enable near-atomic-resolution single-particle cryo-EM

Water gelation by small organic molecules.

Human serum albumin: from bench to bedside.

J-aggregates are useful model systems for investigations about photosynthesis and photoactive bacteria [1]. The achiral monomeric benzimidocarbocyanine C8O3 (Fig. 1) forms optically active J-aggregates in aqueous solution [2]. Their chiral supramolecular structure can be influenced by cationic and anionic amphiphiles which is shown by vis-, circular dichroism (CD)-spectroscopy and cryo-electron microscopy (cryo-EM).

Vis- and CD-spectroscopic studies of the interaction of amphiphiles with optically active J-aggregates

Molecular monolayer rods and tubules made of .alpha.-(L-lysine),.omega.-(amino) bolaamphiphiles

The first self-organized quadruple helices consisting of monopolymeric material have been obtained from N-octyl- and N-dodecyl-D-gluconamides in water. The have been characterized by electron microscopy, image analysis, and computer modelling. The pitch of helices is equal to (2π×molecular bilayer diameter); their gradient conforms with the magic angle (54.7 o ). The quadruple helices rearrange in aqueous gels to a single helix made of circular 4-fold layers of molecules, a pitch of 7.4 nm, and a gradient of 82±3 o

Magic angle (54.7.degree.) gradient and minimal surfaces in quadruple micellar helices

https://hal.archives-ouvertes.fr/hal-00501657/document

Physicochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of l-α-dimyristoyl phosphatidylcholine

Easily accessible protoporphyrin IX 13,17-bis(glycosamides) form colloidal aqueous solutions which are stable for several months or longer. Electron micrographs show ribbons of an approximate width of 4 nm and lengths of between 20 nm (D-glucosamide) and 5 μm (D,L-mannosamide). In one case, gel chromatography was applied in order to acquire the molecular weight, which was determined to be ≥2×10 6 D for about 90% of the colloidal particles. The UV-vis spectra of the aqueous suspension show a Soret band which is split by about 100 nm by exciton interactions (460 and 360 nm)

Chiral micellar porphyrin fibers with 2-aminoglycosamide head groups

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