Biomedical subjects

Z Siwy

Publications and source records attributed to Z Siwy.

4 recordsLinked to original sources

PubMed2005

Asymmetric diffusion through synthetic nanopores.

We show that diffusion currents for a membrane containing a single conical nanopore with a fixed surface charge and small enough opening diameter depend on the concentration gradient direction. We interpret the results based on the effect of salt concentration on the thickness of the electrical double layer within the nanopore associated with the nanopore's surface charge and the distribution of electric fields inside the pore. The experimental observations are described by a diffusional model based on the Smoluchowski-Nernst-Planck equation.

Chlorine↗

PubMed2002

Fabrication of a synthetic nanopore ion pump.

We present a synthetic nanodevice, which transports potassium ions against their concentration gradient if stimulated with external field fluctuations. It consists of a single, conical pore, created in a thin polyethylene terephthalate film. The pumping mechanism is similar to one of longitudinally oscillating deterministic ratchets.

Journal Article↗

PubMed2002

Origin of 1/f(alpha) noise in membrane channel currents.

The transport characteristics of nanofabricated synthetic pores of similar dimensions to those of biological channels is reported. By comparison of the ion current through single synthetic and biological channels we show that the 1/f(alpha) noise indeed originates from the channel's opening-closing process. Strong evidence has been provided that the latter is related to the underlying motions of channel wall constituents.

Animals↗

PubMed1999

Statistical analysis of ionic current fluctuations in membrane channels.

The statistical analysis of an ionic current signal recorded from a single channel of a biological membrane is presented. We find the main characteristics of the ionic current probability density, the closed- and open-state distributions, and the autocorrelation function of the current recordings by using procedures based on the kernel and tail estimators, the bootstrap methodology; and the Zipf plots. The results provide evidence for the non-Markovian character of the channel kinetics of the investigated data.

Animals↗