Remarked Kleem (online): "Endy envisions plant-based environmental monitors, programmed tissues and even medical devices that "make Fantastic Voyage come true," (Kleem, 04.02.13). In the first (grainy) image below, Endy's DNA "buffer gates" flash different colors according to their situation. In the image below that, we have a string of DNA -- we see the code of the a's, C's, T's and G's -- that has been programmed by synthetic biologist Eric Winfree of the California Institute of Technology --.

(Excerpted from Keim, B Computers Made Out of DNA, Slime and Other Strange Stuff

Wired. http://www.wired.com/wiredscience/2013/04/strange-computers/?pid=6598&viewall=true)

Timothy Lu, a researcher at the Massachusetts Institute of Technology, is taking this idea further by building cellular computers that can, for instance, program cells to automatically investigate bowels for cancer. Here DNA is transplanted to computer to help the computer achieve medical miracles (Brumfiel, 2013)

The idea of DNA in conjunction with computer can, therefore, be used in two ways: DNA can be used to revolutionize computer and computer ideas can be integrated into the DNA circuitry of the human -- or animal -- cell.

The Future of DNA Computers

The first DNA computers are likely to be used by governments for cracking secret codes, or by airlines wanting to work out better air- routes. They may also be used by neuroscientists for analyzing the brain and by scientists for unraveling medical or other mysteries. According to Lovgren (2003), in fact, there is no end to the possibilities to which the new technology could be used: bacterial cells, for example, are excellent at 'sniffing out' pathogens or chemicals, such as heavy metals. They could for used for elements such as this and by redesigning the circuitry of bacteria, we can produce cheap biosensors that may even monitor quality of water as well as of other things.

Endy, meanwhile, suggests that we could one day have: " living bridges or buildings constructed by the self-directed growth of their natural materials, controlled by internal biological circuits, or even tiny medical "submarines" with on-board DNA computers navigating the insides of our bodies." (Heaven 02 April 2013).

Its limitations?

DNA computers are excellent in working with mathematical problems but there are still limitations that have to be worked around. Aran Nayebi, for instance, was able to implement Strassen's matrix multiplication...

Caltech researchers, too, were able to create a circuit made from 130 different DNA strands, which calculated the square root of digits up to 15 (Strain, 2011 )). DNA computing, however, does not contribute anything new to computability theory where problems are computationally solvable using different models of computation. But these limitations pale in contrast to the revolutionary mass of contributions that DNA computer can theoretically bring to human and general development.
Amos in the Encyclopedia Britannica, for instance, opines that:

By harnessing the power of molecules, new forms of information-processing technology are possible that are evolvable, self-replicating, self-repairing, and responsive. The possible applications of this emerging technology will have an impact on many areas, including intelligent medical diagnostics and drug delivery, tissue engineering, energy, and the environment. (DNA computing http://www.britannica.com/EBchecked/topic/941575/DNA-computing)

DNA computerization will herald a new age. There is no end to the uses that DNA biochips can be expended for.

Let's hope that it will be used ethically and wisely.

Sources

Brumfiel, G (March 29, 2013) Tiny DNA Switches Aim to Revolutionize 'Cellular' Computing. NPR. http://www.npr.org/2013/03/29/175604770/tiny-dna-switches-aim-to-revolutionize-cellular-computing

Lovgren, Stefan (2003-02-24). Computer Made from DNA and Enzymes. National Geographic. http://news.nationalgeographic.com/news/2003/02/0224_030224_DNAcomputer.html

Heaven D (02 April 2013) DNA transistors pave way for living computers Newscientishttp://www.newscientist.com/article/dn23337-dna-transistors-pave-way-for-living-computers.html

Strain D (June 2, 2011 ) Flexible DNA computer finds square roots Science News http://www.sciencenews.org/view/generic/id/330621/description/Flexible_DNA_computer_finds_square_roots_

Ehrenburg, R (January 23, 2013 ) DNA stores poems, a photo and a speech . Science News http://www.sciencenews.org/view/generic/id/347702/description/DNA_stores_poems_a_photo_and_a_speech

Bonsor, K (nd) How DNA Computers Will Work. How stuff works.com http://computer.howstuffworks.com/dna-computer3.htm

Olympus Optical Co., Ltd. (2002) Development of World's First DNA Computer for Gene Analysis

http://www.olympus-global.com/en/news/2002a/nr020128dnacome.jsp