Cryo-FIB Machining: An Alternative to TEM Cryo-Sections Cut with Diamonds?

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7-August 11, 201

Correction to "Luminescent Gold Nanocluster-Decorated Polymeric Hybrid Particles with Assembly-Induced Emission"

Correction to “Luminescent Gold Nanocluster-Decorated Polymeric Hybrid Particles with Assembly-Induced Emission

Ruthenium-decorated lipid vesicles: light-induced release of [Ru(terpy)(bpy)(oh2)]2+ and thermal back coordination

Electrostatic forces play an important role in the interaction between large transition metal complexes and lipid bilayers. In this work, a thioether-cholestanol hybrid ligand (4) was synthesized, which coordinates to ruthenium(II) via its sulfur atom and intercalates into lipid bilayers via its apolar tail. By mixing its ruthenium complex [Ru(terpy)(bpy)(4)]2+ (terpy = 2,2′;6′,2′′-terpyridine; bpy = 2,2′-bipyridine) with either the negatively charged lipid dimyristoylphosphatidylglycerol (DMPG) or with the zwitterionic lipid dimyristoylphosphatidylcholine (DMPC), large unilamellar vesicles decorated with ruthenium polypyridyl complexes are formed. Upon visible light irradiation the ruthenium−sulfur coordination bond is selectively broken, releasing the ruthenium fragment as the free aqua complex [Ru(terpy)(bpy)(OH2)]2+. The photochemical quantum yield under blue light irradiation (452 nm) is 0.0074(8) for DMPG vesicles and 0.0073(8) for DMPC vesicles (at 25 °C), which is not significantly different from similar homogeneous systems. Dynamic light scattering and cryo-TEM pictures show that the size and shape of the vesicles are not perturbed by light irradiation. Depending on the charge of the lipids, the cationic aqua complex either strongly interacts with the membrane (DMPG) or diffuses away from it (DMPC). Back coordination of [Ru(terpy)(bpy)(OH2)]2+ to the thioether-decorated vesicles takes place only at DMPG bilayers with high ligand concentrations (25 mol %) and elevated temperatures (70 °C). During this process, partial vesicle fusion was also observed. We discuss the potential of such ruthenium-decorated vesicles in the context of light-controlled molecular motion and light-triggered drug delivery

In situ imaging of field-induced hexagonal columns in magnetite ferrofluids.

Field-induced structures in a ferrofluid with well-defined magnetite nanoparticles with a permanent magnetic dipole moment are analyzed on a single-particle level by in situ cryogenic transmission electron microscopy (2D). The field-induced columnar phase locally exhibits hexagonal symmetry and confirms the structures observed in simulations for ferromagnetic dipolar fluids in 2D. The columns are distorted by lens-shaped voids, due to the weak interchain attraction relative to field-directed dipole-dipole attraction. Both dipolar coupling and the dipole concentration determine the dimensions and the spatial arrangement of the columns. Their regular spacing manifests long-range end-pole repulsions that eventually dominate the fluctuation-induced attractions between dipole chains that initiate the columnar transition

Binary superlattices of PbSe and CdSe nanocrystals

In this paper we show that self-organization of colloidal PbSe and CdSe semiconductor nanocrystals with a size ratio of 0.57 leads to binary structures with a AB2 or a cuboctahedral AB13 lattice. The type of superlattice formed can be regulated by the relative concentration of both nanocrystals in the suspension

Ethenylene-bridged periodic mesoporous organosilicas with ultra-large mesopores

E-configured ethenylene-bridged periodic mesoporous organosilicas with ultra-large mesopores and unprecedented pore volumes have been developed for the first time

Luminescent Gold Nanocluster-Decorated Polymeric Hybrid Particles with Assembly-Induced Emission

Ultrasmall gold atom clusters (<2 nm in diameter) or gold nanoclusters exhibit emergent photonic properties (near-infrared absorption and emission) compared to larger plasmonic gold particles because of the significant quantization of their conduction band. Although single gold nanocluster properties and applications are being increasingly investigated, little is still known about their behavior and properties when assembled into suprastructures, and even fewer studies are investigating their use for biomedical applications. Here, a simple synthetic pathway combines gold nanoclusters with thermosensitive diblock copolymers of poly(ethylene glycol) (PEG) and poly( N-isopropylacrylamide) (PNIPAm) to form a new class of gold-polymer, micelle-forming, hybrid nanoparticle. The nanohybrids' design is uniquely centered on enabling the temperature-dependent self-assembly of gold nanoclusters into the hydrophobic cores of micelles. This nonbulk assembly not only preserves but also enhances the attractive near-infrared photonics of the gold nanoclusters by significantly increasing their native fluorescent signal. In parallel to the fundamental insights into gold nanocluster ordering and assembly, the gold-polymer nanohybrids also demonstrated great potential as fluorescent live-imaging probes in vitro. This innovative material design based on the temperature-dependent, self-assembly of gold nanoclusters within a polymeric micelle's core shows great promise toward bioassays, nanosensors, and nanomedicine