A lecture about our research:

DNA and Proteins-Based Nanoelectronics

Conductivity through one-dimensional nanowires is a central theme in nanoelectronics. DNA and its derivatives (such as metalized DNA, G-quadruplex DNA and more) are leading candidates for application as molecular nanowires due to the double-strand recognition that allows self-assembly, the accurate synthesis of the molecule, the enormous density of information packing in DNA bases and the well-established enzymatic machinery that allow to manipulate these molecules.  In another route, we also develop nanoelectronics devices that are based on proteins and their hybrids with nanoparticles.  
We investigate the morphology and electrical properties of molecules that we develop in collaboration with other groups, to achieve nanowires that will have the self-assembly properties together with considerably improved conductivity.
The conductivity along single molecules is monitored by several techniques:


Direct electrical measurements through DNA with metal nano-electrodes

Nano-electrodes with a small gap are fabricated on silicon surfaces using e-beam lithography. A DNA molecule bound to metallic nanoparticles from both sides is brought to the electrodes and electrical measurements through the DNA are performed. This technique is expanded for the development of rapid, ultra-sensitive and mobile single-molecule based DNA and RNA detectors.

Danny Porath

Conductive atomic force microscopy (cAFM)

A conductive AFM measurement setup is employed for measuring 10-10000 nm long molecules and wires on hard surfaces. For this purpose, a stationary gold electrode with a sharp border is evaporated over part of the molecules/wires. The conductive AFM tip serves as a second mobile electrode for contacting molecules/wires protruding from under the gold electrode at different distances. The electrical properties of additional nanowires, such as carbon nanotubes and perovskite nanowires are also studied with the system.

Scanning tunneling microscopy (STM) and spectroscopy (STS)

The DNA energy level spectra are investigated by scanning tunneling microscopy/spectroscopy. These measurements are carried out at small distances of ~1 nm from the molecule. These tunneling-regime measurements reveal a high resolution image of the molecule and its local density of states.

Physical approaches and tools to address biological questions

Hybrid nanopores for single-molecule sensing

A nanopore is a pore of nanometer size that is formed in a membrane between two solutions. Nanopores have become an important tool for detection and analysis of molecules and are utilized for DNA sequencing, analytes sensing and other uses. We develop hybrid nanopores that combine between solid state nanopores (which are based on thin membranes made of silicon and other materials) and peptides or proteins, to achieve nanopores with improved sensitivity and stability.

Ultrasensitive biomarkers detection at the single molecule level

One of the central challenges of humanity is the prediction, prevention, and early detection of diseases, cancer in particular. A possible path to meet this challenge is the development of highly sensitive methods for early detection of disease biomarkers. Biomarkers are a measurable characteristic that represents an alteration of the physiology of an individual in relation to risk factors for a disease, its progression and treatment associated outcome. We develop an ultrasensitive method for detecting biomarkers at the single molecule level using nanoparticles. Our method is based on capturing the target biomarkers with nanoparticles (that are covered with ligands that can bind the biomarkers at high specificity) and detection of the nanoparticles with single molecule imaging methods such as electron microscope and nanopores.

Danny Porath