Subsections

• 6.4.1.1 DNA Structure

6.4.1 DNAFET

The ability of ISFETs to sense the charge in deoxyribonucleic acid (DNA) can be exploited to craft biosensors able to detect specific DNA sequences [189,196,208]. This possibility has a vast impact in many areas, like food and environmental monitoring, development of patient-specific drugs, and gene expression experiments. Therefore, the simulation of so called DNAFETs is currently extremely interesting. However, in order to give a better overview about DNAFETs, a small introduction to DNA and the currently established detection methods will be given prior to the simulation results.

6.4.1.1 DNA Structure

DNA and proteins are regularly addressed as the main active components in all living organisms[228]. The DNA stores via molecular sequences in the polymere all genetic information. Watson and Crick found that DNA consists of a double helix structure. Each helix is a compound of a repeating structure, containing a sugar polymer, a nitrogen base and a phosphate ion. The nitrogen base can be one of four select bases. Namely, adenine (A), thymin (T), cytosine (C), and guanine (G). A DNA strand may consist of several millions of such base pairs and the specific sequence of bases within the DNA strand allows to encode specific genetic information concerning an organism. A species signature can be build from particular subsequences of an organism's DNA, thus providing a genetic finger print [189,228]. The two helical strands are bound together by weak hydrogen bonds formed between the bases. The bonds between A and T, and between C and G have been found to be thermodynamical favorable. Therefore, only helical DNA strands with complementary bases will be able to fully bind and form a thermodynamically stable compound. The process of double helix formation, called hybridization, is a fundamental part in the life cycle of any living organism, facilitating the multiplication of genetic code.