Continuous observation of the stochastic motion of an individual small-molecule walker.

Motion--whether it the ability to change shape, rotate or translate--is an important potential asset for functional nanostructures. For translational motion, a variety of DNA-based and small-molecule walkers have been created, but observing the translational motion of individual molecules in real time remains a significant challenge. Here, we show that the movement of a small-molecule walker along a five-foothold track can be monitored continuously within a protein nanoreactor.

Rates and stoichiometries of metal ion probes of cysteine residues within ion channels.

Metal ion probes are used to assess the accessibility of cysteine side chains in polypeptides lining the conductive pathways of ion channels and thereby determine the conformations of channel states. Despite the widespread use of this approach, the chemistry of metal ion-thiol interactions has not been fully elucidated. Here, we investigate the modification of cysteine residues within a protein pore by the commonly used Ag(+) and Cd(2+) probes at the single-molecule level, and provide rates and stoichiometries that will be useful for the design and interpretation of accessibility experiments.

The effects of microenvironment polarity and dendritic branching of aliphatic hydrocarbon dendrons on the self-assembly of 2-ureido-4-pyrimidinones.

Two series of aliphatic hydrocarbon-based G1-G3 dendritic 2-ureido-4-pyrimidinones (UPy) (S-Gn)₂ and (L-Gn)₂, differing from one another by the distance between the branching juncture to the urea end, were prepared and characterized. These hydrocarbon dendrons were also appended to a p-aminonitrobenzene solvatochromic chromophore in order to probe their microenvironment polarity. While positive solvatochromism was observed which indicated the chromophore was solvent accessible, there was no significant difference between the microenvironment polarities on going from the G1 to the G3 dendrons.