Optimization of Detergent-Mediated Reconstitution of Influenza A M2 Protein into Proteoliposomes.

We report the optimization of detergent-mediated reconstitution of an integral membrane-bound protein, full-length influenza M2 protein, by direct insertion into detergent-saturated liposomes. Detergent-mediated reconstitution is an important method for preparing proteoliposomes for studying membrane proteins, and must be optimized for each combination of protein and membrane constituents used. The purpose of the reconstitution was to prepare samples for site-directed spin-labeling electron paramagnetic resonance (SDSL-EPR) studies.

Collective fluorescence enhancement in nanoparticle clusters.

Many nanoscale systems are known to emit light intermittently under continuous illumination. In the fluorescence of single semiconductor nanoparticles, the distributions of bright and dark periods ('on' and 'off' times) follow Lévy statistics. Although fluorescence from single-quantum dots and from macroscopic quantum dot ensembles has been studied, there has been little study of fluorescence from small ensembles.

Facts and artifacts in the blinking statistics of semiconductor nanocrystals.

Since its initial discovery just over a decade ago, blinking of semiconductor nanocrystals has typically been described in terms of probability distributions for durations of bright, or "on," states and dark, or "off," states. These distributions are obtained by binning photon counts in order to construct a time series for emission intensity and then applying a threshold to distinguish on states from off states. By examining experimental data from CdSe/ZnS core/shell nanocrystals and by simulating this data according to a simple, two-state blinking model, we find that the apparent truncated power-law distributions of on times can depend significantly on the choices of binning time and threshold.

Blinking statistics correlated with nanoparticle number.

We report fluorescence of single semiconductor nanorods (NRs) and few-NR clusters, correlated with transmission electron microscopy for direct determination of the number of NRs present in a single fluorescent source. For samples drop-cast from dilute solutions, we show that the majority of the blinking sources (approximately 75%) are individual NRs while the remaining sources are small clusters consisting of up to 15 NRs. Clusters containing two or three NRs exhibit intermittent fluorescence intensity trajectories, I(t), similar to those of individual NRs.

High-density regular arrays of nanometer-scale rods formed on silicon surfaces via femtosecond laser irradiation in water.

We report on the formation of high-density regular arrays of nanometer-scale rods using femtosecond laser irradiation of a silicon surface immersed in water. The resulting surface exhibits both micrometer-scale and nanometer-scale structures. The micrometer-scale structure consists of spikes of 5-10 mum width, which are entirely covered by nanometer-scale rods that are roughly 50 nm wide and normal to the surface of the micrometer-scale spikes.

Fluorescence blinking statistics from CdSe core and core/shell nanorods.

We report fluorescence blinking statistics measured from single CdSe nanorods (NRs) of seven different sizes with aspect ratios ranging from 3 to 11. This study also included core/shell CdSe/ZnSe NRs and core NRs with two different surface ligands producing different degrees of surface passivation. We compare the findings for NRs to our measurements of blinking statistics from spherical CdSe core and CdSe/ZnS core/shell nanocrystals (NCs).

Visible and near-infrared responsivity of femtosecond-laser microstructured silicon photodiodes.

We investigated the current-voltage characteristics and responsivity of photodiodes fabricated with silicon that was microstructured by use of femtosecond-laser pulses in a sulfur-containing atmosphere. The photodiodes that we fabricated have a broad spectral response ranging from the visible to the near infrared (400-1600 nm). The responsivity depends on substrate doping, microstructuring fluence, and annealing temperature.