Basically, it is the smallest pH meter in the world, but its impact on science, medicine, and even daily life is likely to be huge. The pH meter developed by Ion Torrent sits on a semiconductor chip beneath very tiny wells containing a single-stranded DNA probe and DNA polymerase in a buffer. The wells are flooded by the nucleotides A, T, G and C in a sequential manner, and incorporation is recorded by measuring the proton released in the reaction. Thereby, the pH meter can be used to sequence DNA. The chip contains 1.3 million wells, the device measures about 60x50x55 cm (24x20x21 inches), costs $50,000 and is named PGM – Personal Genome Machine.
Already on the market, it puts DNA sequencing within the reach of nearly every lab, doctor’s practice, clinic, and even college. While it still has certain limitations – it can read only 20 genes at once at present – DNA sequencing never has been easier and less error-prone. Other devices with similar elegance and even more speed are around the corner – as an example, scientists from Imperial College of London last month demonstrated in NanoLetters that they can sequence genes by propelling a DNA strand at high speed through a tiny 50 nanometre (nm) hole cut in a silicon chip, using an electrical charge. As the strand emerges from the nanopore, its coding sequence is read by a ‘tunnelling electrode junction’. This 2 nm gap between two wires supports an electrical current that interacts with the distinct electrical signal from each base code. The speed is unbelievable and translates into sequencing an entire human genome in 5 minutes.
Certainly, these machines will have a huge impact on the amount of data generated for the development of personalized medicine and individualized therapies. But now that DNA sequencing is approaching a mass market, it will inevitably reach anyone, just like cameras, computers and mobile phones that turned from “professional only” machines into commodities. The statement that no one needs such a machine is refuted by history: when the telephone was invented, US president Rutherford B. Hayes could not think of anyone wanting to use it, XEROX once was sure that the world market for photocopiers would be around 50 machines, and even Intel’s founder Gordon Moore could not think of using personal computers at home for anything meaningful other than “maybe filing cooking recipes”.
What would you do with a personal sequencer at home? Screen your blood for disease on a daily basis? Check your food for microbial contamination? Classify the bugs and shrubs in your garden to find new ones? Secretly sequence the DNA of you neighbors, boss or affair to find out about genetic weaknesses? In a decade, ads might state once again: “There is an APP for that!”