Hi,
I am just having some issues with the principles of "Ion Semiconductor Sequencing" by Ion Torrent. As far as I understood it, the release of a hydrogen ion during polymerization is detected and knowing which nucleotide was added the sequence can be inferred.
My problem is, that during polymerization, it's not just a hydrogen ion that comes up, but also one OH-, forming H2O, as shown on this picture.
I think this formation of H2O happens instantly, so I am wondering how the detection of the hydrogen ion is possible. Are the sensors that sensitive that they can detect the hydrogen ion before H20 is formed?
I would be grateful for any answers, as I have not found anything about this "problem" yet and all graphics and explanations are totally based on "release of H+ is detected" not mentioning this theme at all...
Many thanks in advance!!
1 answer
Well, part of the problem is that your image doesn't really show what's going on:
You can read the whole paper here. So in short, the hydrogen isn't immediately bound to a hydroxl group. If you look at figure 1 from their paper, you can get an idea of the bulk kinetics and amplitudes involved.
Edit: I should emphasize the fixed charge that's created. That's what's actually inducing the charge movement in the plate that the voltage clamp is picking up.
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