Many of these developments, such as the joint research from Columbia University and University of Pennsylvania referenced above and work at Harvard University from late last year, have improved the electronics that boost the faint signal generated when DNA passes through the nanopore. Both of these research teams turned away from the more common method of slowing the DNA down as it passes through the nanopore.
In research coming out of the University of Washington, it seems that slowing down the DNA as it passes through the nanopore has been revisited as a method for improving the signal and identifying the DNA. But in so doing, the researchers developed a unique method that combines a specially adapted, highly sensitive nanopore with a molecular motor.
"We augmented a protein nanopore we developed for this purpose with a molecular motor that moves a DNA strand through the pore a nucleotide at a time," says Jens Gundlach, a University of Washington physics professor who leads the research team, in a press release covering the research. “The motor pulls the strand through the pore at a manageable speed of tens of milliseconds per nucleotide, which is slow enough to be able to read the current signal.”
The research, which was published in the 25 March online version of Nature Biotechnology, demonstrated how an enzyme that is associated with the replication of a virus could serve as the molecular motor. While researchers at the University of California Santa Cruz had produced this molecular motor before, this time Gundlach and his colleagues attached the motor to a more sensitive kind of nanopore that could distinguish different nucleotide types.
Gundlach believes that this unique combination of molecular motor and highly sensitive nanopore could be used to identify epigenetic DNA modifications, in which DNA is modified within a specific individual.
"Epigenetic modifications are rather important for things like cancer," he said. Being able to provide DNA sequencing that can identify epigenetic changes "is one of the charms of the nanopore sequencing method."
Figure: University of Washington