Synthesis and properties of water-soluble gold colloids covalently derivatized with neutral polymer monolayers.

Citrate-capped gold nanoparticles as well as planar gold surfaces can be efficiently grafted with a covalently attached polymer monolayer a few nanometers thick, by simple contact of the metal surface with dilute aqueous solutions of hydrophilic polymers that are end-capped with disulfide moieties, as shown by UV/vis absorption, dynamic light scattering, and surface plasmon resonance studies. The hydrophilic polymer-coated gold colloids can be freeze-dried and stored as powders that can be subsequently dissolved to yield stable aqueous dispersions, even at very large concentrations. They allow for applying filtrations, gel permeation chromatography, or centrifugation.

HCl causes less intracellular acidification in Necturus gastric mucosa surface epithelial cells than other acids.

Luminal acid causes intracellular acidification in the gastric epithelium, but the mechanism by which H(+) enters surface cells remains obscure. This study addressed the problem by assessing how different acids affect intracellular pH in gastric surface cells. Isolated Necturus maculosus antral mucosa was exposed to HCl, HNO(3), H(2)SO(4), and H(3)PO(4) at pH 2.

Highly efficient immobilisation of antibody fragments to functionalised lipid monolayers.

The covalent attachment of Fab' fragments of polyclonal anti-human IgG to a lipid with a terminal linker group was examined by means of quartz crystal microbalance and surface plasmon resonance measurements. The linker lipid was embedded in binary or ternary monolayers of dipalmitoylphosphatidylcholine (DPPC) and cholesterol. Atomic force microscopy images of the films deposited on silanised SiO(2) substrates showed that Fab' fragments take a standing position, thus giving site-directed immobilisation.

Atomic force microscope images of lipid layers spread from vesicle suspensions.

The layer formation of unilamellar vesicles of L-alpha-dimyristoyl phosphatidylcholine (DMPC) spread onto the air/liquid interface has been investigated. The layers were transferred to clean glass slides and onto slides made hydrophobic with multilayers of Cd arachidate. Aged vesicle suspensions aggregate during storage and are transferred as large domains as imaged with atomic force microscopy (AFM).