Biomedical subjects

Michael Zwolak

Publications and source records attributed to Michael Zwolak.

5 recordsLinked to original sources

PubMed2006

Fast DNA sequencing via transverse electronic transport.

A rapid and low-cost method to sequence DNA would usher in a revolution in medicine. We propose and theoretically show the feasibility of a protocol for sequencing based on the distributions of transverse electrical currents of single-stranded DNA while it translocates through a nanopore. Our estimates, based on the statistics of these distributions, reveal that sequencing of an entire human genome could be done with very high accuracy in a matter of hours without parallelization, that is, orders of magnitude faster than present techniques. The practical implementation of our approach would represent a substantial advancement in our ability to study, predict, and cure diseases from the perspective of the genetic makeup of each individual.

Biosensing Techniques↗

PubMed2005

Dynamical corrections to the DFT-LDA electron conductance in nanoscale systems.

Using time-dependent current-density functional theory, we derive analytically the dynamical exchange-correlation correction to the dc conductance of nanoscale junctions. The correction pertains to the conductance calculated in the zero-frequency limit of time-dependent density functional theory within the adiabatic local-density approximation. In particular, we show that in linear response, the correction depends nonlinearly on the gradient of the electron density; thus, it is more pronounced for molecular junctions than for quantum point contacts. We provide specific numerical examples to illustrate these findings.

Journal Article↗

PubMed2005

Inelastic effects on the transport properties of alkanethiols.

Using first-principles approaches, we investigate local heating and the inelastic contribution to the current for various alkanethiols sandwiched between metal electrodes. In the absence of good heat dissipation into the bulk electrodes, we find that the local temperature of the alkanethiols is relatively insensitive to their length. This is due to the rates of heating and cooling processes scaling similarly with length. On the other hand, when considering heat dissipation into the bulk electrodes, the local temperature of alkanethiols decreases as their length increases. We also find that the inelastic scattering profile displays an odd-even effect with length which compares well with experimental results. This effect is due to the alternating direction of the CH(3) group motion with respect to current flow with increasing C atoms in the chain and is very sensitive to the structure of the carbon-sulfur-gold bond. Inelastic scattering profiles can therefore help illuminate the bonding configuration of molecules to metallic surfaces.

Journal Article↗

PubMed2005

Electronic signature of DNA nucleotides via transverse transport.

We report theoretical studies of charge transport in single-stranded DNA in the direction perpendicular to the backbone axis. We find that, if the electrodes which sandwich the DNA have the appropriate spatial width, each nucleotide carries a unique signature due to the different electronic and chemical structure of the four bases. This signature is independent of the nearest-neighbor nucleotides. Furthermore, except for the nucleotides with guanine and cytosine bases, we find that the difference in conductance of the nucleotides is large for most orientations of the bases with respect to the electrodes. By exploiting these differences it may be possible to sequence single-stranded DNA by scanning its length with conducting probes.

Biosensing Techniques↗

PubMed2004

Mixed-state dynamics in one-dimensional quantum lattice systems: a time-dependent superoperator renormalization algorithm.

We present an algorithm to study mixed-state dynamics in one-dimensional quantum lattice systems. The algorithm can be used, e.g., to construct thermal states or to simulate real time evolution given by a generic master equation. Its two main ingredients are (i) a superoperator renormalization scheme to efficiently describe the state of the system and (ii) the time evolving block decimation technique to efficiently update the state during a time evolution. The computational cost of a simulation increases significantly with the amount of correlations between subsystems, but it otherwise depends only linearly on the system size. We present simulations involving quantum spins and fermions in one spatial dimension.

Journal Article↗