It just happen to me the other day - why 454 is stuck with the design put forth by Rothberg eons ago? It has so many limitations that essentially kill any possibility for its further development. Correct me if I am wrong, but 454 still has the longest read capability that is not matched by any other platform, at least reliably. I think it is a great advantage of the platform and it is a shame that Roche fails to bank on this pushing further development much more agrressively.
The major limitation seems the platform throughput, which is essentially cast in stone (glass) because it is directly connected to the geometry of PTP, primarily to the linear density of reactors. But why it cannot be increased? If Ion Torrent guys can pack much more those reactors on a much smaller chip, why 454 cannot? GS chunior plate is about the same size and protocols are substantially simpler than for the big boy, so why not take this boy and make it competitive?
Has it something to do with optical interference for signal detection? I am not expert here at all, but I thought that CCD with a much higher resolution can be deployed. As result of further miniaturization, Ion Torrent can use tiny beads for its chips, which enabled automatization of emPCR by running it in a pouch. Going this way eventually limits read length, though, since tiny bubbles in emPCR can hold only limited amount of reagents, so amplification of long fragments becomes problematic. But a golden middle can be found, I am sure. The current method uses roughly 30 micron beads, while Ion Torrent uses something in micron size, so there is a lot of room for improvement. Yet, just 10-fold increase in reactor density will put 454 right in the throughput range of most popular platforms, 3.5 Gb to 35 Gb, but with undisputable advantage of long reads. What dou you, guys, think?
The major limitation seems the platform throughput, which is essentially cast in stone (glass) because it is directly connected to the geometry of PTP, primarily to the linear density of reactors. But why it cannot be increased? If Ion Torrent guys can pack much more those reactors on a much smaller chip, why 454 cannot? GS chunior plate is about the same size and protocols are substantially simpler than for the big boy, so why not take this boy and make it competitive?
Has it something to do with optical interference for signal detection? I am not expert here at all, but I thought that CCD with a much higher resolution can be deployed. As result of further miniaturization, Ion Torrent can use tiny beads for its chips, which enabled automatization of emPCR by running it in a pouch. Going this way eventually limits read length, though, since tiny bubbles in emPCR can hold only limited amount of reagents, so amplification of long fragments becomes problematic. But a golden middle can be found, I am sure. The current method uses roughly 30 micron beads, while Ion Torrent uses something in micron size, so there is a lot of room for improvement. Yet, just 10-fold increase in reactor density will put 454 right in the throughput range of most popular platforms, 3.5 Gb to 35 Gb, but with undisputable advantage of long reads. What dou you, guys, think?
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