Resistive-pulse detection of multilamellar liposomes.

The resistive-pulse method was used to monitor the pressure-driven translocation of multilamellar liposomes with radii between 190 and 450 nm through a single conical nanopore embedded in a glass membrane. Liposomes (0% and 5% 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (sodium salt) in 1,2-dilauroyl-sn-glycero-3-phosphocholine or 0%, 5%, and 9% 1,2-dipalmitoyl-sn-glycero-3-phospho(1'-rac-glycerol) (sodium salt) in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine) were prepared by extrusion through a polycarbonate membrane. Liposome translocation through a glass nanopore was studied as a function of nanopore size and the temperature relative to the lipid bilayer transition temperature, T(c).

The role of the electrical double layer and ion pairing on the electrochemical oxidation of hexachloroiridate(III) at Pt electrodes of nanometer dimensions.

The steady-state voltammetric oxidation of hexachloroiridate(III), IrCl6(3-) (1-5 mM), in the presence and absence of an excess supporting electrolyte was investigated at disk- and hemispherical-shaped Pt electrodes with radii ranging from 48 nm to 12.5 microm. Thermodynamic, kinetic, and transport parameters that define the shape and magnitude of the voltammetric wave exhibit a complex dependence on whether a supporting electrolyte is present in the solution.

Zeptomole voltammetric detection and electron-transfer rate measurements using platinum electrodes of nanometer dimensions.

The characterization of quasi-hemispherical Pt electrodes of nanometer dimensions (radius 2-150 nm), prepared by electrophoretic coating of etched Pt wires with poly-(acrylic acid), is described. The goals of these experiments are to estimate the accuracy of using steady-state voltammetric limiting currents (i(lim)) in determining the true electrode area and to develop new electrochemical methods for rapidly screening individual electrodes for non-ideal geometries. Electrochemical active areas were determined by measuring the electrical charge (Q) associated with oxidation of adsorbed bis(2,2'-bipyridine)chloro(4,4'-trimethylenedipyridine)osmium(II) in fast-scan voltammetric measurements (scan rate 1000 V/s).