The future of DNA in Nanotechnology. Avisek Chatterjee CHEM 750

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1 The future of DNA in Nanotechnology Avisek Chatterjee CHEM 750

2 Outline what is DNA? DNA Technology Proposed applications of DNA in nanotech Nanotechnology founder s view. References

3 What is DNA?

4 DNA stands for: D: Deoxyribose N: Nucleic A: Acid DNA is too small to see, but under a microscope it looks like a twisted up ladder! Every living thing has DNA. That means that you have something in common with a zebra, a tree, a mushroom and a beetle!!!!

5 What is DNA? It is stored inside the cell nucleus of living organisms. All living things contain DNA!!!!! The main goal of DNA in the cell is long-term storage of information. Various enzymes act on DNA & copy its information into either more DNA, in DNA replication, or transcribe & translate it into protein. Encodes the sequence of amino acid residues in protein.

6 Structure of DNA DNA is a long chain polymer of simple chemical units called nucleotides. Which are held together by a backbone made of sugar and phosphate groups. The backbone carries four types of molecules called bases (purines & pyrimidines). Kim, et al., Cell 84:

7 DNA Structure Hydrogen bonded nucleotides on opposite sides. DNA helices are antiparallel. Carbon & sugar define ends..5 & 3. Pyrimidines bond with purines. T A C G Kim, et al., Cell 84:

8 DNA Structure Helical structure of DNA Major & minor groves. 10Å radius & 20Å diameter 3.4Å between nucleotide base pairs. 34Å / 360 turn. 10 nucleotide base pairs / 360 turn. The process that forms double helix is called DNA hybridization. The order or sequence of these bases along the chain forms the genetic code. Kim, et al., Cell 84:

9 DNA contains all the information necessary to make a complete organism. DNA is organized into genes. Cells decode the information to build proteins. Each protein carries out unique function.

10 Proteins work together to carry out cell functions.

11 DNA Technology

12 DNA technology DNA technology involves the concepts of : Restriction enzymes Nucleic acid electrophoresis DNA polymorphism.

13 Restriction enzymes Each restriction enzymes cuts the DNA into defined fragments by acting at specific target molecules. These enzymes act as scissors, cutting the DNA into specific sites. Restriction enzymes are commonly available. IPGRI and Cornell University, 2003

14 Nucleic acid Electrophoresis A method to separate DNA fragments to allow their visualization and/or identification. IPGRI and Cornell University, 2003

15 DNA polymorphism Various events give rise to variants, more or less complex, in the DNA sequence. Such variants are usually described as polymorphism. Point mutation, rearrangement.

16 Why DNA is in nanotech? Size ~1nm. Information storage ability. Biosensing. Suitable to be used as nanoscale construction material as proposed in the famous bottom up approach. Chris Dwyer Assistant Professor

17 Proposed applications of DNA in Nanotechnology

18 Future computing Chemical nanocomputing: Computing is based on chemical reactions (bond breaking & bond making) Inputs are encoded in the molecular structure of the reactants and outputs are can be extracted from the structure of the products. DNA computing is most promising in this respect.

19 DNA computers!!!!!! Why limit ourselves to electronics???? DNA the molecule of life can store vast quantities data in its sequence of four bases (A,G,T,C). & natural enzymes can manipulate this information. In 1994 Adleman showed that DNA based computer can solve a problem which is particularly difficult for ordinary computers. Introduction of DNA computers.

20 Devices go molecular Molecular & Electronics Currently fabricated with CMOS transistors. Higher transistor density--- faster circuit performance. Limitation towards higher integration is restricted by current lithographic techniques, heat dissipation etc. Search for a novel technology--- leads us towards Molecular electronics. Use individual molecules as wires, switches, rectifiers & memories.

21 DNA the prospective candidate! Charge transport in DNA & the feasibility of constructing DNA based devices Development of novel bioelectronics systems. Molecular recognition & special structuring that suggests its use for self assembly. Molecular recognition drives the fabrication of devices & integrated circuits. Self assembly drives the design of well structured systems.

22 Bioelectronics Two potential applications have been up to now envisioned for DNA: (i) as template in molecular electronic circuits, and (ii)as wiring system (molecular wire). It has been proven that charge can propagate through DNA!!

23 Biosensors

24 DNA biosensors Target DNA molecules are captured at the recognition layer and the resulting hybridization signal is transduced into a usable electronic signal for display and analysis. Applications: diagnosis, therapy selection & follow up of severe diseases. Nature Biotechnology,21, 10, Oct 2003

25 Consists of three single strands of synthetic DNA. When the fourth DNA is added to the test tube it grabs the unpaired bases and zips the tweezers shut. Test tube based nanofabrication. DNA nanotweezers

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27 References Nature Biotechnology,21,10,Oct Charge transport in DNA-based Devices, Danny Porath, Noa Lapidot & Gomez- Herrero. Nanotechnolog,Quan Zhou,Helsinki University of Technology. T.G.Drummond,M.G.Hill & J.K.Barton, Nature Biotechnology,21,10,2003.

28 Thank you I would like to Thank Prof. K.T.Leung & all of you for your kind attention