טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentNir Hadar
SubjectDNA Manipulations for Sensing and Scaffolding
DepartmentDepartment of Chemistry
Supervisors Professor Yoav Eichen
Professor Gadi Schuster
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

Many DNA based nanotechnology applications are enabled due to available enzymatic manipulation tools and due to the unique structure, unusual chemistry and physical properties of the DNA molecule. This work deals with DNA manipulations in two different fields of applications:

I.  DNA bio-sensing - Development of novel SNP detection methods

Single Nucleotide Polymorphisms (SNPs) are the most common genetic mutations in the human genome and provide important genetic markers to identify many hereditary diseases. We have developed very simple, selective and sensitive methods for SNP detection based on the DNA polymerase reaction that selectively incorporates biotinylated nucleotide at the SNP site and three different detection methods that do not require PCR amplification. We combine bio catalyzed precipitation with simple, inexpensive visual detection color change with low detection limit of 200 amoles (~30 million molecules) by naked eye, and an ultra-sensitive surface plasmon resonance (SPR) technology that allow the detection of as low as 0.5 amoles (~300,000 molecules). In the third detection method  we localize straptavidine-nanogold on the biotinylated DNA, which serve as nucleation center for further gold deposition. These gold spots can be detected by electrical measurements, and can be used as an interface to the electronic world.

II. Molecular electronics

DNA is a preferable candidate for molecular electronics. Since DNA molecules are insulators on a nanometric scale, the idea is to use the molecular recognition and self-assembly ability of DNA to construct DNA scaffolds that serve as templates to localize conductor molecules and species at an accurate address on the DNA.

In this work, we developed two biosynthesis methods using in vivo and in vitro manipulation to construct figure-eight-like structures of ss-DNA and ds-DNA molecules having a relatively high yield, which could be used further as a scaffold for nanotechnology applications.

In another project, we developed a method for the selective metallization of artificial DNA duplexes to yield highly uniform and size-tunable nanowires. We utilized modified uridine/cytosine derivative carries an aldehyde groups to specifically and selectively labeled DNA which enables programming of the metallization location on the selected DNA sequence. In a two-step metallization procedure the artificial DNA template was coated with a homogeneous and dense gold or silver layer. The present route may serve as a method for the sequence-specific metallization of artificial DNA strands, which could be of great use in the fabrication of nano-scale electrical building blocks.