Ion Torrent Chemistry

Ion Torrent pairs semiconductor technology with a simple sequencing chemistry that is based on a well-characterized biochemical process. In nature, when a nucleotide is incorporated into a strand of DNA by a polymerase, a hydrogen ion is released as a byproduct. Ion Torrent uses a high-density array of micro-machined wells to perform this biochemical process in a massively parallel way. Each well holds a different DNA template. Beneath the wells is an ion-sensitive layer and beneath that a proprietary Ion sensor. Here's how the technology is used to call a base: If a nucleotide, for example a C, is added to a DNA template and is then incorporated into a strand of DNA, a hydrogen ion will be released. The charge from that ion will change the pH of the solution, which can be detected by our proprietary ion sensor. Our sequencer—essentially the world's smallest solid-state pH meter—will call the base, going directly from chemical information to digital information. The Ion Personal Genome Machine (PGM™) sequencer then sequentially floods the chip with one nucleotide after another. If the next nucleotide that floods the chip is not a match. No voltage change will be recorded and no base will be called. If there are two identical bases on the DNA strand, the voltage will be double, and the chip will record two identical bases called. Because this is direct detection—no scanning, no cameras, no light—each nucleotide incorporation is recorded in seconds.

Category:

Science & Technology

Tags:

• ion
• torrent
• iontorrent
• sequencing
• sequencer
• nextgen
• ion_torrent
• Personal_Genome_Machine
• PGM
• next_generation_sequencing

[DNAutics]

@152czar actually, it's not. Well, no more than photolithography that's been around for years.

[paulszauter]

Nature 475, 348–352 (21 July 2011)

[Achillies11ify]

Don't forget that the core technology was not developed by Rothberg (Ion torrent), his company has a non-exclusive license from the true inventor Prof Chris Toumazou

[onroadcowboy]

There're two issues of this technology:

- The synthesis cycle: we can only add one kind of nucleotides at each cycle and therefore, the total number of cycles is increased.

- The error rate because of sequence by context: with repeated sequence of single nucleotide, the machine has to measure the signal strength, and with little difference in voltage, the error taken is certain.

[squeeg1985]

@onroadcowboy It is the same voltage (relatively), however the machine has reservoirs of each nucleotide and will flood the wells of the chip with one nucleotide at a time...

[152czar]

holy shit this is pretty advanced nanotechnology

[onroadcowboy]

Dear friend,

Please let me know how can the machine distinguish between nucleotides? Actually, the signal is the same - voltage isn't it?

[nmolonia]

Simple question: why am I watching a commercial instead of reading about it in a scientific publication?